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/README.md

@@ -59,8 +59,8 @@ validation runs.
 | Right flipper | Keypad Enter | Right Ctrl, `D`, or Right arrow |
 | Nudge | Space, Left Shift, keypad `3` | Right Shift aliases keypad `3` |
 | Help | F1 | Enter/Escape returns |
-| Settings | F2 | - |
-| High scores | F3 | - |
+| Settings | `TDKPIN.INI` before launch | F10 opens the portable settings screen |
+| High scores | Automatic when a player finishes | F9 opens the portable table viewer |
 | Sound | F12 | - |
 
 The five original speed choices remain available in settings. Physics now uses