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/panels/StatusBarPanel.h

@@ -93,7 +93,7 @@ static void renderStatusBar(EditorState& state) {
 
     // Left cluster: mode, language, encoding, line ending
     std::string modeLabel = state.active()
-        ? (state.active()->bufferMode == BufferManager::BufferMode::Text ? "Text" : "Structured")
+        ? (state.active()->bufferMode == BufferManager::BufferMode::Text ? "Text Mode" : "Structured Mode")
         : "-";
     if (ImGui::Button(modeLabel.c_str())) {
         toggleBufferMode(state);