fix(physics): port the Borland Real48 collision core

Add a bit-exact six-byte Real48 implementation for integer conversion,
rounding, comparison, add/subtract, multiply/divide, and Newton square root.
Use the normalized Borland random-register result and route speed clamps,
segment/circle detection, moving flippers, captures, triggers, and magnetic
fields through the recovered arithmetic instead of host floating formulas.

Preserve Real48 spin per ball and feed it through the original tangent/spin
response, separating zero-spin C fixtures from retained-spin Wine traces.
Replace path-progress selection with surface-distance ordering and implement
dynamic records 174/175, including impulse transfer to the other slot,
normal_velocity-1000 response, and the second post-collision speed clamp.

Test Plan:
- `cargo test --all-targets` -- passed, 69 tests
- `cargo clippy --all-targets -- -D warnings` -- passed
- `rumdl check tdkpin-rs/CHANGELOG.md tdkpin-rs/RECONSTRUCTION.md` -- passed
- `git diff --cached --check` -- passed

tdkpin-rs/RECONSTRUCTION.md

@@ -24,7 +24,7 @@ implementation.
 | Help and languages | Exact | Original resource images 1001-1005 are displayed directly. |
 | Playfield collision layout | Recovered | All 109 active type-2 line objects and 40 static active type-1 circles are transcribed from the original 175-object registration table. The registration routine converts its sideways inputs with `screen = (y, x - 20)` and accumulates explicitly relative objects. Type-2 records retain every recovered Real48 normal/tangent response pair and registered one-sided orientation. Type-1 records retain their swept-circle radius, radial rebound, tangent coupling, and bumper kick. Each flipper uses its exact two line records plus moving tip circle in both positions. Moving-flipper contact ports `1000:7ed9` rather than fitting live samples: delta-specific pivots/edges, integer cross gates, radial/penetration calculations, response-record gain, and position/velocity publication are tested against all four C harness directions and the raised release geometry. Object 174 is overwritten with the live first ball and Rust handles its ball-to-ball role directly. |
 | Ball launcher and nudge input | Recovered | The initial 32-bit fixed-point coordinates decode to `(325, 413)` in the right shooter lane. Each Down keydown subtracts `15*50 = 750` millipixels, release subtracts another `15*100 = 1500`, and the result follows the recovered randomized `-3800` lower and `-2280` weak upper clamp branches. The ten decoration frames use the same strict 750-millipixel thresholds. Left Shift and keypad 3 apply their directional `(50-Random(20))*15` impulses; Space uses the recovered Real48 horizontal factor and `(60-Random(20))*15` vertical impulse. Each nudge adds 25 to the wrapping 16-bit tilt counter, compares it with `30+Random(10)`, and the detail timer decrements a nonzero counter once per callback. |
-| Physics arithmetic | Recovered gameplay behavior | Production movement uses the original 10 ms millipixel substep, `+15` vertical acceleration, `3800` speed bound, point-path type-2 intersection, one-sided line response, swept type-1 circle response, and swept non-physical sensor contacts. It evaluates all records and applies the earliest contact along the substep. The original Borland seed update and high-word `Random(n)` mapping drive launcher variation, effects, claw terminals, and the recovered randomized magnetic-field impulse. Radius-bearing type-4 triggers retain a separate transient entry flag and independently scale X and Y by `1.03-Random*0.08`. Type-3 capture records retain their per-player 16-bit contact word, deep-inside threshold, pull/hold progression to age 300, first-contact sound, and `99`/`2` completion sentinels. Live probes cover ordinary rails, ordinary circles, a kicked bumper, lock holes, magnetic fields, all claw exits, and both flipper directions. |
+| Physics arithmetic | Recovered Real48 core | Production movement uses the original 10 ms millipixel substep, `+15` vertical acceleration, Real48 `3800/speed` clamp, type-2 distance/cross gates, type-1 midpoint normal, surface-distance candidate ordering, persistent Real48 spin, and the common impulse response. Dynamic records 174/175 transfer normal impulse to the other ball before applying `normal_velocity-1000` to the moving ball. The original Borland seed update, high-word `Random(n)`, and normalized Real48 random register result drive launcher variation, effects, claw terminals, magnetic fields, and trigger response. Type-4 triggers retain a separate transient entry flag; type-3 captures retain per-player 16-bit contact words, deep-inside pull/hold progression to age 300, first-contact sound, and `99`/`2` completion sentinels. Zero-spin C harnesses and retained-spin Wine probes are tested separately rather than conflated. |
 | Rules | Recovered gameplay paths | Player count, controls, the five three-line bumper-value groups, four three-line TDK-diamond groups, five doubling-value lock holes, wheel-reset target, seven-way effect selector/consumer including multiball, permanent double scoring, and four exact media/extra-ball thresholds follow original help/code paths, globals, and object flags. The ninth diamond pays the original 24,464 completion value; the following completed bank enables double scoring, and later completions add 100,000 to the per-player secondary score. Turn changes mirror the original save/load of all 175 collision record states: wheel/top targets, active/contact slots, selected effect, and multiball readiness remain attached to their player. Claw contact and all initially active type-4 targets use recovered records. The top three targets score 500 each and independently enable the left, center, or right magnetic field record; each field pulls the ball upward until it exits and then deactivates. The claw state machine and release table have live differential coverage for all four random terminals. Remaining timing uncertainty is presentation batching at non-default detail settings, not gameplay routing. |
 | Numeric scoring | Recovered gameplay values | Static scores come from the initialized 175-object ledger. Dynamic bumper progression, target-bank completion, diamond awards, 10k-160k lock bonuses, 310k transfer, six effect values, multiball mode, and all four media thresholds are transcribed from `1000:b476`, `1000:c4e1`, `1000:bc36`, and live state probes. Lock and effect awards share the original per-player secondary score and display multiplier; the fifth hole transfers and clears it, increments the multiplier, and grants the recovered ball award. Score mutation uses the original 32-bit wrapping behavior, and each add operation can advance at most one media threshold. |
 | High scores | Recovered visible flow; portable storage | The original 276-byte table is decoded as ten `IWIK`-XOR-obfuscated little-endian scores plus ten 22-byte names. Each player is checked immediately when their own last ball is lost; qualifying scores use the original signed-high/unsigned-low comparison and a `TDK Pinball Player`-prefilled name screen before the table is shown and play resumes. Persisted updates use portable JSON rather than rewriting the Win16 file. |
@@ -71,10 +71,9 @@ decoded, build-ready subset; it does not replace that evidence archive.
   operates both flippers from ball position. The two-minute acceptance run
   covers repeated launches, both flippers, targets, bumpers, lock holes, a claw
   capture/release pair, and drains while checking every state for finite values.
-- Semantic boundary: gameplay routes and initialized values are covered, but no
-  claim is made that every remaining host `f64` intermediate or repaint tick is
-  binary-identical to Borland Real48 and Win16 GDI execution. Non-default repaint
-  batching remains a documented platform difference.
+- Semantic boundary: collision, random, spin, and fixed-point state now use the
+  reconstructed Borland arithmetic and rounding model. Win16 GDI execution and
+  non-default repaint batching remain platform-level presentation differences.
 
 ## Architecture
 
@@ -83,5 +82,7 @@ decoded, build-ready subset; it does not replace that evidence archive.
 - `game.rs`: fixed-step game state, recovered walls, rules, and scoring;
 - `geometry.rs`: segment/circle collision primitives;
 - `original_physics.rs`: millipixel integration and recovered type-2 responses;
+- `real48.rs`: bit-exact Borland six-byte arithmetic, conversion, and square root;
+- `flipper_physics.rs`: reconstructed moving-flipper geometry and response;
 - `table.rs`: source-traceable collision objects recovered from the Win16 table;
 - `persistence.rs`: platform paths, settings, high scores, and legacy import.