fix: add file cycling in multi-file permission prompt

[nitishagar]

Issue for this PR

Closes #21914

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

When apply_patch edits multiple files, the permission prompt concatenates all diffs into one blob with no way to review individual files. The per-file data (metadata.files[]) was already being sent by apply_patch but the EditBody component ignored it, only reading the concatenated metadata.diff string.

This adds [ and ] keybinds to cycle through files one at a time in the permission prompt:

• Extracts the files array from metadata.files in EditBody
• When multiple files are present, shows one file's diff at a time with a file indicator bar ("Patched src/foo.ts 2/5")
• ] cycles to the next file, [ cycles to the previous, with wrap-around
• Adds a [ ] files hint in the prompt footer when in multi-file mode
• Single-file edits are unchanged (no files array present, falls through to existing behavior)

How did you verify your code works?

• Ran bun run typecheck — no new type errors (only pre-existing TS7006 from unresolved @opentui/solid types)
• Verified single-file edit path is unchanged (no files array → existing concatenated diff behavior)
• Reviewed that [/] keyboard handling follows the same pattern as existing cycling keybinds (agent_cycle, session_child_cycle)

Screenshots / recordings

N/A — TUI change, needs manual testing with "edit": "ask" permission config and a multi-file edit prompt.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR