Add db migrations, update watch.sh for uv + idempotent runs

- Schema versioned with migrations table
- watch.sh runs db migrations on every pull
- watch.sh uses uv run/sync instead of pip
- Fixed parser.py reference in watch.sh

db.py

@@ -15,10 +15,10 @@ def get_db() -> sqlite3.Connection:
     return conn
 
 
-def init_db():
-    """Create tables if they don't exist."""
-    conn = get_db()
-    conn.executescript("""
+SCHEMA_VERSION = 2
+
+MIGRATIONS = {
+    1: """
         CREATE TABLE IF NOT EXISTS repos (
             name TEXT PRIMARY KEY,
             url TEXT,
@@ -34,7 +34,7 @@ def init_db():
             language TEXT,
             documentation TEXT,
             prev_documentation TEXT,
-            functions TEXT,  -- JSON array
+            functions TEXT,
             last_commit TEXT,
             staleness TEXT DEFAULT 'fresh',
             updated_at TEXT
@@ -54,9 +54,42 @@ def init_db():
         CREATE INDEX IF NOT EXISTS idx_files_staleness ON files(staleness);
         CREATE INDEX IF NOT EXISTS idx_rels_staleness ON relationships(staleness);
         CREATE INDEX IF NOT EXISTS idx_rels_to ON relationships(to_file);
-    """)
+    """,
+    2: """
+        CREATE TABLE IF NOT EXISTS schema_version (
+            version INTEGER PRIMARY KEY
+        );
+    """,
+}
+
+
+def init_db():
+    """Create or migrate the database schema."""
+    conn = get_db()
+
+    # Check current version
+    try:
+        row = conn.execute("SELECT MAX(version) AS v FROM schema_version").fetchone()
+        current = row["v"] or 0
+    except sqlite3.OperationalError:
+        current = 0
+
+    if current >= SCHEMA_VERSION:
+        conn.close()
+        return
+
+    # Run pending migrations
+    for v in range(current + 1, SCHEMA_VERSION + 1):
+        if v in MIGRATIONS:
+            print(f"  [db] Running migration v{v}...")
+            conn.executescript(MIGRATIONS[v])
+
+    # Ensure schema_version table exists and record version
+    conn.execute("CREATE TABLE IF NOT EXISTS schema_version (version INTEGER PRIMARY KEY)")
+    conn.execute("INSERT OR REPLACE INTO schema_version (version) VALUES (?)", (SCHEMA_VERSION,))
     conn.commit()
     conn.close()
+    print(f"  [db] Schema at v{SCHEMA_VERSION}")
 
 
 class GraphDB: