Steps 266-268: Phase 10a — semantic annotation core + sidecar persistence (32/32 tests)

Step 266: 5 semantic annotation AST types (Intent, Complexity, Risk,
Contract, SemanticTag) with JSON roundtrip and compact AST integration.
Step 267: Sidecar AST persistence (.whetstone/<file>.ast.json) with
save/load/list RPC methods, MCP tools, and permission enforcement.
Step 268: Phase 10a integration tests — multi-file sidecar workflow,
all 5 types in compact view, idempotent roundtrip, source isolation.

Also includes Sprint 10 plan, GUI/installer polish, and Emacs integration fixes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

editor/src/BufferOpsProjection.h

@@ -74,7 +74,7 @@ inline void EditorState::openDiff(const std::string& beforeText,
     bool preview,
     int action,
     const std::vector<std::string>& transformIds,
-    const std::vector<BatchMutationAPI::Mutation>& batchMutations = {}) {
+    const std::vector<BatchMutationAPI::Mutation>& batchMutations) {
     diff.active = true;
     diff.preview = preview;
     diff.action = action;