feat: Add full-text search with FTS5

Implements FTS5-based full-text search for notes as specified in ADR-034.

Changes:
- Created migration 005_add_fts5_search.sql with FTS5 virtual table
- Created starpunk/search.py module with search functions
- Integrated FTS index updates into create_note() and update_note()
- DELETE trigger automatically removes notes from FTS index
- INSERT/UPDATE handled by application code (files not in DB)

Features:
- Porter stemming for better English search
- Unicode normalization for international characters
- Relevance ranking with snippets
- Graceful degradation if FTS5 unavailable
- Helper function to rebuild index if needed

Note: Initial FTS index population needs to be added to app startup.
Part of v1.1.0 (Phase 3).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

starpunk/notes.py

@@ -286,6 +286,17 @@ def create_note(
     # Create Note object
     note = Note.from_row(row, data_dir)
 
+    # 9. UPDATE FTS INDEX (if available)
+    try:
+        from starpunk.search import update_fts_index, has_fts_table
+        db_path = Path(current_app.config["DATABASE_PATH"])
+        if has_fts_table(db_path):
+            update_fts_index(db, note_id, slug, content)
+            db.commit()
+    except Exception as e:
+        # FTS update failure should not prevent note creation
+        current_app.logger.warning(f"Failed to update FTS index for note {slug}: {e}")
+
     return note
 
 
@@ -676,7 +687,19 @@ def update_note(
             f"Failed to update note: {existing_note.slug}",
         )
 
-    # 6. RETURN UPDATED NOTE
+    # 6. UPDATE FTS INDEX (if available and content changed)
+    if content is not None:
+        try:
+            from starpunk.search import update_fts_index, has_fts_table
+            db_path = Path(current_app.config["DATABASE_PATH"])
+            if has_fts_table(db_path):
+                update_fts_index(db, existing_note.id, existing_note.slug, content)
+                db.commit()
+        except Exception as e:
+            # FTS update failure should not prevent note update
+            current_app.logger.warning(f"Failed to update FTS index for note {existing_note.slug}: {e}")
+
+    # 7. RETURN UPDATED NOTE
     updated_note = get_note(slug=existing_note.slug, load_content=True)
 
     return updated_note