Fix db_init for non-owner DB users

ALTER TABLE, CREATE INDEX and CREATE OR REPLACE FUNCTION all require table/function
ownership in PostgreSQL. Replace IF NOT EXISTS DDL with explicit existence checks so
db_init works for unprivileged application users where the schema was created by a
different role (e.g. postgres).

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

main.py

@@ -411,28 +411,37 @@ def db_init(cur):
       updated_ts          timestamptz NOT NULL DEFAULT now()
     );
     """)
-    cur.execute("""
-    ALTER TABLE remote_cam.import_job
-      ADD COLUMN IF NOT EXISTS needs_ocr_backfill boolean NOT NULL DEFAULT false;
-    """)
-    cur.execute("""
-    ALTER TABLE remote_cam.import_job
-      ADD COLUMN IF NOT EXISTS needs_exif_backfill boolean NOT NULL DEFAULT false;
-    """)
-    cur.execute("CREATE INDEX IF NOT EXISTS import_job_needs_ocr_idx ON remote_cam.import_job(needs_ocr_backfill);")
-    cur.execute("CREATE INDEX IF NOT EXISTS import_job_needs_exif_idx ON remote_cam.import_job(needs_exif_backfill);")
-    cur.execute("CREATE INDEX IF NOT EXISTS import_job_status_idx ON remote_cam.import_job(status);")
-    cur.execute("CREATE INDEX IF NOT EXISTS import_job_updated_idx ON remote_cam.import_job(updated_ts);")
+    for col, typedef in [
+        ("needs_ocr_backfill",  "boolean NOT NULL DEFAULT false"),
+        ("needs_exif_backfill", "boolean NOT NULL DEFAULT false"),
+    ]:
+        cur.execute("""
+            SELECT 1 FROM information_schema.columns
+            WHERE table_schema='remote_cam' AND table_name='import_job' AND column_name=%s
+        """, (col,))
+        if not cur.fetchone():
+            cur.execute(f"ALTER TABLE remote_cam.import_job ADD COLUMN {col} {typedef};")
+    for idx, col in [
+        ("import_job_needs_ocr_idx",  "needs_ocr_backfill"),
+        ("import_job_needs_exif_idx", "needs_exif_backfill"),
+        ("import_job_status_idx",     "status"),
+        ("import_job_updated_idx",    "updated_ts"),
+    ]:
+        cur.execute("SELECT 1 FROM pg_indexes WHERE schemaname='remote_cam' AND indexname=%s", (idx,))
+        if not cur.fetchone():
+            cur.execute(f"CREATE INDEX {idx} ON remote_cam.import_job({col});")
 
-    cur.execute("""
-    CREATE OR REPLACE FUNCTION remote_cam.set_updated_ts()
-    RETURNS trigger AS $$
-    BEGIN
-      NEW.updated_ts = now();
-      RETURN NEW;
-    END;
-    $$ LANGUAGE plpgsql;
-    """)
+    cur.execute("SELECT 1 FROM pg_proc JOIN pg_namespace ON pg_proc.pronamespace=pg_namespace.oid WHERE nspname='remote_cam' AND proname='set_updated_ts'")
+    if not cur.fetchone():
+        cur.execute("""
+        CREATE FUNCTION remote_cam.set_updated_ts()
+        RETURNS trigger AS $$
+        BEGIN
+          NEW.updated_ts = now();
+          RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """)
     cur.execute("""
     DO $$
     BEGIN