feat(11-01): add tags table to schema with migration and push script

- Add polymorphic tags table (entity_type/entity_id/name) with unique
  index on (entity_type, entity_id, name) and lookup index on
  (entity_type, entity_id) — pattern follows comments table (D-05/D-06/D-07)
- Add Tag/NewTag types and tagsRelations (no direct FK, query-time join)
- Hand-write src/db/migrations/0006_add_tags_table.sql following the
  established project convention (drizzle-kit generate is unusable here —
  meta/_journal.json snapshots out of sync since 0001, pre-existing since
  Phase 8) and add journal entry for 0006_add_tags_table
- Add scripts/push-11-tags-migration.ts (idempotent CREATE TABLE/INDEX IF
  NOT EXISTS) with production deploy note for manual SSH+docker exec apply

src/db/migrations/meta/_journal.json

@@ -15,6 +15,13 @@
       "when": 1781151516000,
       "tag": "0001_add_services_table",
       "breakpoints": true
+    },
+    {
+      "idx": 6,
+      "version": "7",
+      "when": 1781442000000,
+      "tag": "0006_add_tags_table",
+      "breakpoints": true
     }
   ]
 }