fix(ui): preserve original idle view and function keys

Remove the invented attract-screen instruction panel so idle mode presents the
original table artwork without a modern overlay. Keep the original plus-key
start flow and automatic high-score presentation.

Stop assigning F2 and F3 to modern screens; those keys are normally inactive in
the original executable outside dormant debug paths. Retain optional portable
settings and high-score viewers on F10 and F9, documenting them as additional
host controls rather than original behavior.

Test Plan:
- `cargo test --all-targets` -- passed, 70 tests
- `cargo clippy --all-targets -- -D warnings` -- passed
- `rumdl check CHANGELOG.md README.md RECONSTRUCTION.md` -- passed
- `git diff --cached --check` -- passed

tdkpin-rs/RECONSTRUCTION.md

@@ -29,7 +29,7 @@ implementation.
 | 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. |
 | Configuration | Behaviorally compatible | Sound, language, and five detail levels are retained. Storage moves from a local Win16 INI file to the platform user-data directory. |
-| Windows UI shell | Deliberately modernized | Win16 menus, modal dialogs, GDI blitting, and multimedia timers are replaced by a fixed native window with keyboard overlays. The visible game and original help render one-for-one at the original 640x460 pixels. |
+| Windows UI shell | Original gameplay surface with native host shell | Win16 window ownership and GDI calls are replaced by a fixed native window, but the visible game, idle table, help resources, automatic per-player high-score flow, original keys, and 640x460 logical pixels are retained. F2/F3 remain unassigned as in normal original operation; optional portable settings and table viewers use F10/F9 and do not replace gameplay input. |
 
 ## Extracted asset inventory