fix(f11): address code review — insertion anchoring, turnId, accept-all coverage (#43)

Code-review follow-up on the F11 branch (5966907..1564ef5). Three real findings:

- CRITICAL — pure-insertion hunks were born-orphaned. A document rewrite that
  INSERTS text produced a zero-width hunk (start==end) → buildFingerprint yields
  empty fp.text → anchorer.resolve orphans an empty needle → the proposal could
  never be accepted (silently). diffToHunks now anchors every zero-width
  insertion to an adjacent source token (anchorInsertion): the range absorbs the
  token and the replacement keeps it, so net text is identical but fp.text is
  non-empty and resolvable. New unit tests: applying hunks always reconstructs
  the rewrite (substitute/delete/insert/multi); insertions are never zero-width.
  New host E2E ACCEPTS a rewrite-with-insertion end to end and asserts accept-all
  reconstructs the intended document (also covers sequential multi-hunk accept).

- IMPORTANT — renderPlain cross-block fidelity. The per-block off-mode rendering
  (SLICE-2) can't resolve a reference-link definition in a separate block.
  Documented as a conscious tradeoff of the operator-locked block-level mapping
  (§6.7) — renderReview already rendered per-block, so this keeps both modes
  consistent — with a characterization test + a docstring note.

- MINOR — F11 proposals now carry a turnId (one per Ask-Claude gesture, shared
  across a document rewrite's N hunks), matching the editor-menu editSelection
  path so a rewrite groups as one agent turn.

208 unit + 9/9 F11 host E2E green. (The lone red E2E is a pre-existing,
F11-independent undoMarks timing flake — proven by isolation: it fails
identically with all F11 tests removed.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/trackChangesPreview.ts

@@ -56,6 +56,11 @@ export class TrackChangesPreviewController implements vscode.Disposable {
     const { runEditTurn } = await import("./liveTurn");
     return runEditTurn(instruction, text);
   };
+  /** Monotonic per-session counter minting a stable turnId for each Ask-Claude gesture. */
+  private turnSeq = 0;
+  private nextTurnSeq(): number {
+    return ++this.turnSeq;
+  }
 
   constructor(
     private readonly diffView: DiffViewController,
@@ -219,6 +224,9 @@ export class TrackChangesPreviewController implements vscode.Disposable {
     instruction: string,
   ): Promise<string[]> {
     const full = document.getText();
+    // One turnId per gesture — the document case's N hunk-proposals all share it,
+    // so a single rewrite groups as one agent turn (parity with editSelection).
+    const turnId = `turn-${this.nextTurnSeq()}`;
     const provenance = (turn: EditTurnResult) =>
       ({ kind: "agent" as const, id: "claude", agent: { sdk: "@cline/sdk", model: turn.model, sessionId: turn.sessionId } });
     if (target.kind === "range") {
@@ -226,14 +234,14 @@ export class TrackChangesPreviewController implements vscode.Disposable {
       const turn = await this.editTurn(instruction, selected);
       if (turn.replacement === "" || turn.replacement === selected) return [];
       const fp = buildFingerprint(full, { start: target.start, end: target.end });
-      const id = await this.proposals.propose(document, fp, turn.replacement, provenance(turn), { instruction });
+      const id = await this.proposals.propose(document, fp, turn.replacement, provenance(turn), { turnId, instruction });
       return id ? [id] : [];
     }
     const turn = await this.editTurn(instruction, full);
     const ids: string[] = [];
     for (const h of diffToHunks(full, turn.replacement)) {
       const fp = buildFingerprint(full, { start: h.start, end: h.end });
-      const id = await this.proposals.propose(document, fp, h.replacement, provenance(turn), { instruction });
+      const id = await this.proposals.propose(document, fp, h.replacement, provenance(turn), { turnId, instruction });
       if (id) ids.push(id);
     }
     return ids;