fix(tui): capture keystrokes in search input mode

[mikeyobrien]

Summary

Search mode in ralph-tui was non-functional: pressing / set search_state.search_mode = true but no key-interception block existed, so typed query characters fell through to map_key and dispatched as normal keybindings. Concretely:

• Typing a query containing e fired the new export action (added today in 3454c62).
• The footer never showed the query or an N/M match counter.
• n / N / Esc were inert no-ops.

The state layer (search, next_match, clear_search) and footer rendering were already correct and unit-tested — the snapshot harness calls state.search() directly, so it bypassed the broken interactive path, which is why CI stayed green. Today's export keybindings (e/E) are what made the orphaned search-input path visibly collide.

Fix

• Add handle_search_input, a testable helper invoked from the event loop right after the guidance interception block:
  • Char/Backspace edit the query and live-update matches
  • Enter commits a non-empty query (keeping query/matches so n/N navigate) or clears an empty one
  • Esc cancels and clears the search
• StartSearch seeds an empty query so the footer shows the Search: prompt immediately; the footer omits the match count while the query is empty.
• Wire with_urgent_steer_path into the guidance_test example so the ! urgent-steer path is exercisable in-process.

Tests

• 7 new regression tests in app.rs drive the full interactive path the snapshot harness bypassed (typing, backspace, commit, navigate, cancel, no-op-when-inactive).
• cargo test -p ralph-tui: all pass (242 unit + snapshots/integration). Full workspace builds clean.

Verification

Found by the verify-tui-ux tmux workflow and re-verified live:

/reviewing -> "Search: reviewing 1/20"
n          -> "Search: reviewing 2/20"
Esc        -> search cleared, normal footer restored

No export file is written while typing reviewing (proving e no longer leaks to the export action).

🤖 Generated with Claude Code