Add landlord-override DB migrations (0215 data + 0216 schema)

Splits the DB migration artifacts off the frontend branch so they can
land independently:

- 0215_invert_column_mapping: one-shot data migration inverting
  bulk_address_uploads.column_mapping from header->field to field->header
  (drops 'skip' entries). One-shot — see file header and ADR-0003.
- 0216_add_subtask_service: adds sub_task.service (nullable text) to tag
  which pipeline a subtask belongs to (address2uprn vs
  landlord_description_overrides).

Includes the subtask.ts schema source for 0216 so drizzle's snapshot
stays consistent. No app code depends on these yet.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/db/migrations/0215_invert_column_mapping.sql

@@ -0,0 +1,22 @@
+-- One-shot inversion of bulk_address_uploads.column_mapping.
+--
+-- Old shape: { "<source header>": "<internal field>" } (header -> field), with
+-- unmapped columns stored as "<header>": "skip".
+-- New shape: { "<internal field>": "<source header>" } (field -> header), with
+-- unmapped fields simply absent. See ADR-0003 and the WIP plan (Q2.2/Q5).
+--
+-- 'skip' entries are dropped. On a legacy duplicate (two headers -> one field),
+-- jsonb_object_agg keeps the last header — the new address-uniqueness rule
+-- forbids that going forward anyway. No-op on NULL/empty mappings, so this is
+-- safe regardless of data volume. One-shot: assumes rows are still old-shape.
+UPDATE "bulk_address_uploads"
+SET "column_mapping" = COALESCE(
+  (
+    SELECT jsonb_object_agg(elem.value, elem.key)
+    FROM jsonb_each_text("column_mapping") AS elem
+    WHERE elem.value <> 'skip'
+  ),
+  '{}'::jsonb
+)
+WHERE "column_mapping" IS NOT NULL
+  AND "column_mapping" <> '{}'::jsonb;

src/app/db/migrations/0216_add_subtask_service.sql

@@ -0,0 +1 @@
+ALTER TABLE "sub_task" ADD COLUMN "service" text;

src/app/db/migrations/meta/_journal.json

@@ -1506,6 +1506,20 @@
       "when": 1779969672088,
       "tag": "0214_superb_maelstrom",
       "breakpoints": true
+    },
+    {
+      "idx": 215,
+      "version": "7",
+      "when": 1779991310301,
+      "tag": "0215_invert_column_mapping",
+      "breakpoints": true
+    },
+    {
+      "idx": 216,
+      "version": "7",
+      "when": 1779992128370,
+      "tag": "0216_add_subtask_service",
+      "breakpoints": true
     }
   ]
 }

src/app/db/schema/tasks/subtask.ts

@@ -14,6 +14,10 @@ export const subTasks = pgTable("sub_task", {
 
   status: text("status").notNull().default("In Progress"),
 
+  // Which pipeline this subtask belongs to, e.g. "address2uprn" or
+  // "landlord_description_overrides". NULL = legacy / address. See ADR-0003.
+  service: text("service"),
+
   inputs: text("inputs"), // could later change to JSONB if desired
   outputs: text("outputs"),
   cloudLogsURL: text("cloud_logs_url"),