Smart Context: deep (#1527)

<!-- CURSOR_SUMMARY -->
> [!NOTE]
> Introduce a new "deep" Smart Context mode that supplies versioned
files (by commit) to the engine, adds code search rendering, stores
source commit hashes, improves search-replace recovery, and updates
UI/tests.
> 
> - **Smart Context (deep)**:
> - Replace `conservative` with `deep`; limit context to ~200 turns;
send `sourceCommitHash` per message.
> - Build and pass `versioned_files` (hash-id map + per-message file
refs) and `app_id` to engine.
> - **DB**:
>   - Add `messages.source_commit_hash` (+ migration/snapshot).
> - **Engine/Processing**:
> - Retry Turbo Edits v2: first re-read then fallback to `dyad-write` if
search-replace fails.
> - Include provider options and versioned files in requests; add
`getCurrentCommitHash`/`getFileAtCommit`.
> - **UI**:
>   - Pro mode selector: new `deep` option; tooltips polish.
> - Add `DyadCodeSearch` and `DyadCodeSearchResult` components; parser
supports new tags.
> - **Tests/E2E**:
> - New `smart_context_deep` e2e; update snapshots to include `app_id`
and deep mode; adjust Playwright timeout.
>   - Unit tests for versioned codebase context.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
e3d3bffabb2bc6caf52103461f9d6f2d5ad39df8. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

e2e-tests/fixtures/engine/read-index.md

@@ -0,0 +1,3 @@
+Read the index page:
+<dyad-read path="src/pages/Index.tsx"></dyad-read>
+Done.