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/CHANGELOG.md

@@ -10,6 +10,9 @@ and this project adheres to
 
 ### Fixed
 
+- Remove the invented attract-screen instruction panel and stop assigning the
+  original F2/F3 keys to modern overlays. The idle view is the original table;
+  optional settings/high-score viewers move to F10/F9.
 - Batch physics and flipper publication on the original 50/40/30/20/10-ms
   detail callbacks with exactly 5/4/3/2/1 internal 10-ms substeps, instead of
   exposing every substep on host render frames.