Merge duplicate TUI overlay match arms

[beiwei30]

What changes

Completes the P3-05 mechanical Clippy cleanup for the two approved TUI overlay match_same_arms sites without changing cursor or rendering behavior.

Adds a table-driven regression test that covers every OverlayState cursor-style case, including both permission-request editing modes and no active overlay.

Verification

• scripts/check.sh — passed: documentation audit, rustfmt, Clippy, default and no-default-features checks, public API audit, brand audit, workspace tests, and doctests.
• cargo test -p orbcode-tui overlay_cursor_style — 1 passed.
• cargo test -p orbcode-tui frame_capture — 58 passed.
• cargo clippy -p orbcode-tui --lib -- -W clippy::match_same_arms — the two targeted layout warnings are gone; 18 previously inventoried TUI warnings remain unchanged.
• cargo clippy -p orbcode-tui --all-targets -- -D warnings — passed.
• cargo clippy --workspace --all-targets -- -D warnings — passed.
• cargo test --workspace — passed.
• git diff --check — passed.

Compatibility

• No golden fixture under compat-fixtures/fixtures/ or tui/testdata/ changed.
• No TypeScript-CLI compatibility name was renamed; scripts/audit-brand.sh passes.
• No public API changed; scripts/audit-public-surface.sh passes.
• Behavioral expectations are covered by a test in orbcode-tui.

Notes for the reviewer

This is a mechanical cleanup with no intended user-visible TUI behavior change, so no terminal screenshot is included.

During repeated native-toolchain validation, one WebSocket startup test and one 100ms MCP discovery timing test each timed out once under load. Both passed in isolation and in their full test groups, and the final complete scripts/check.sh run passed.

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