Add repair notes journal with running feed, visibility, and status tagging

New repair_note table for timestamped journal entries on tickets. Each
note captures author, content, visibility (internal or customer-facing),
and the ticket status at time of writing. Notes display as a running
feed on the ticket detail page with newest first. Internal notes have
a lock icon, customer-visible notes highlighted in blue. Supports add
and delete with appropriate permission gating.

packages/backend/src/db/migrations/0018_repair_notes.sql

@@ -0,0 +1,12 @@
+CREATE TYPE "repair_note_visibility" AS ENUM ('internal', 'customer');
+
+CREATE TABLE "repair_note" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+  "repair_ticket_id" uuid NOT NULL REFERENCES "repair_ticket"("id"),
+  "author_id" uuid NOT NULL REFERENCES "user"("id"),
+  "author_name" varchar(255) NOT NULL,
+  "content" text NOT NULL,
+  "visibility" "repair_note_visibility" NOT NULL DEFAULT 'internal',
+  "ticket_status" "repair_ticket_status",
+  "created_at" timestamp with time zone NOT NULL DEFAULT now()
+);

packages/backend/src/db/migrations/meta/_journal.json

@@ -127,6 +127,13 @@
       "when": 1774770000000,
       "tag": "0017_repair_in_transit_status",
       "breakpoints": true
+    },
+    {
+      "idx": 18,
+      "version": "7",
+      "when": 1774780000000,
+      "tag": "0018_repair_notes",
+      "breakpoints": true
     }
   ]
 }