[codex] Fix command palette query focus

[onevcat]

Summary

• Replaces the fragile SwiftUI @FocusState query focus handoff with a thin AppKit-backed query field, following the existing terminal search overlay pattern.
• Reasserts query focus shortly after the palette appears so the macOS 26.5/Tahoe Cmd+P menu-command path cannot leave the terminal as first responder.
• Keeps the existing hidden shortcut buttons for Up/Down and Ctrl-P/Ctrl-N as a fallback path, while the AppKit field also handles Escape, Return, Up/Down, and Ctrl-P/Ctrl-N when focused.
• Restores focus to the selected terminal when the palette is dismissed without switching terminals, including Escape, repeated Cmd+P, and passive command actions such as check-for-updates/refresh/debug toast.
• In Canvas mode, restores focus to the last Canvas-focused terminal card via terminalClient.canvasFocusedWorktreeID().

Root Cause Evidence

The reproduced behavior on macOS 26.5 is specific:

• Cmd+P opens the palette.
• The original palette still received navigation keys: Up/Down moved the selection.
• The query field had no insertion cursor, and typed text continued going to the terminal behind it.
• Clicking the query field made the original implementation work.
• Cmd+Shift+P worked in the original implementation.

That points away from shortcut delivery or overlay presentation, and toward the query field failing to become first responder after the Cmd+P open path. Earlier attempts also ruled out Ghostty keybind routing and upstream menu identity alignment as sufficient fixes.

One intermediate AppKit field version made things worse because it replaced the existing keyboard shortcut fallback and closed the palette on text-field focus churn. This version intentionally avoids that: it preserves the fallback shortcut buttons and does not use blur as a dismiss signal.

Regression Check

• Filtering, selection updates, item activation, row clicks, and recency ordering still use the existing Command Palette reducer and view code paths.
• Up/Down and Ctrl-P/Ctrl-N hidden shortcut buttons are preserved as fallback keyboard routing.
• The query changed surface is limited to query focus and query text input plumbing.
• Terminal focus restoration is routed through TerminalClient.Command.focusSelectedTab.
• Normal/Shelf restore uses selectedTerminalWorktree; Canvas restore uses canvasFocusedWorktreeID; worktree selection explicitly does not restore the previous terminal focus.

Validation

• xcodebuild test -project supacode.xcodeproj -scheme supacode -destination "platform=macOS" -only-testing:supacodeTests/AppShortcutsTests -only-testing:supacodeTests/CommandPaletteFeatureTests -only-testing:supacodeTests/AppFeatureCommandPaletteTests CODE_SIGNING_ALLOWED=NO CODE_SIGNING_REQUIRED=NO CODE_SIGN_IDENTITY="" -skipMacroValidation 2>&1 | xcsift -f toon
• make build-app 2>&1 | xcsift -f toon

Manual Verification

• On macOS 26.5, focus a terminal, press Cmd+P, type a query, and verify the text appears in the Command Palette field rather than the terminal.
• Verify Cmd+P then Up/Down changes palette selection.
• Verify Cmd+P then clicking the query field still allows typing.
• Verify Cmd+Shift+P opens the palette and accepts typing.
• Verify Escape dismisses the palette and returns typing focus to the previous terminal in Normal, Shelf, and Canvas modes.
• Verify repeated Cmd+P dismisses the palette and returns typing focus to the previous terminal in Normal, Shelf, and Canvas modes.
• Verify choosing a passive command, such as debug toast, dismisses the palette and returns typing focus to the previous terminal in Normal, Shelf, and Canvas modes.
• Verify choosing a worktree does not restore focus to the previous terminal.