Fix: seed pre-tracking migrations to skip already-applied 02 and 03

Migration 02 and 03 were applied before the schema_migrations tracking
table existed, so they had no record and the runner tried to re-run them,
hitting non-idempotent TimescaleDB policy/trigger/cagg statements.

seed_pre_tracking_migrations() checks for sentinel schema objects and
inserts records for any migration that was clearly already applied:
  - 02: tracksolid.devices table exists
  - 03: position_history.altitude column exists

Called immediately after ensure_tracking_table() on every startup.
Safe on fresh databases (objects absent → nothing seeded → runs normally).

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

run_migrations.py

@@ -68,6 +68,45 @@ def ensure_tracking_table(conn):
     conn.commit()
 
 
+def seed_pre_tracking_migrations(conn):
+    """
+    Retroactively mark migrations as applied if their schema objects already
+    exist. Required when the tracking table is introduced to a database that
+    was migrated before tracking existed — prevents re-running non-idempotent
+    statements (TimescaleDB policies, triggers, continuous aggregates).
+    """
+    seeds = []
+
+    with conn.cursor() as cur:
+        # Migration 02: tracksolid.devices is the canonical sentinel table
+        cur.execute("""
+            SELECT 1 FROM information_schema.tables
+            WHERE table_schema = 'tracksolid' AND table_name = 'devices'
+        """)
+        if cur.fetchone():
+            seeds.append("02_tracksolid_full_schema_rev.sql")
+
+        # Migration 03: position_history.altitude column added in this migration
+        cur.execute("""
+            SELECT 1 FROM information_schema.columns
+            WHERE table_schema = 'tracksolid'
+              AND table_name   = 'position_history'
+              AND column_name  = 'altitude'
+        """)
+        if cur.fetchone():
+            seeds.append("03_webhook_schema_migration.sql")
+
+        for filename in seeds:
+            cur.execute("""
+                INSERT INTO tracksolid.schema_migrations (filename)
+                VALUES (%s) ON CONFLICT DO NOTHING
+            """, (filename,))
+
+    conn.commit()
+    if seeds:
+        print(f"  Seeded pre-tracking migrations as applied: {', '.join(seeds)}")
+
+
 def already_applied(conn, filename):
     with conn.cursor() as cur:
         cur.execute(
@@ -128,6 +167,7 @@ def main():
 
     conn = get_conn()
     ensure_tracking_table(conn)
+    seed_pre_tracking_migrations(conn)
 
     applied = skipped = 0
     for sql_file in MIGRATIONS: