Implement file storage layer with local provider, upload/download API, tests

- StorageProvider interface with LocalProvider (S3 placeholder)
- File table with entity_type/entity_id references, content type, path
- POST /v1/files (multipart upload), GET /v1/files (list by entity),
  GET /v1/files/:id (metadata), GET /v1/files/serve/* (content),
  DELETE /v1/files/:id
- member_identifier drops base64 columns, uses file_id FKs
- File validation: type whitelist, size limits, per-entity max
- Fastify storage plugin injects provider into app
- 6 API tests for upload, list, get, delete, validation
- Test runner kills stale port before starting backend

packages/backend/src/db/migrations/0012_file_storage.sql

@@ -0,0 +1,25 @@
+-- File storage table
+CREATE TABLE IF NOT EXISTS "file" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  "company_id" uuid NOT NULL REFERENCES "company"("id"),
+  "path" varchar(1000) NOT NULL,
+  "filename" varchar(255) NOT NULL,
+  "content_type" varchar(100) NOT NULL,
+  "size_bytes" integer NOT NULL,
+  "entity_type" varchar(100) NOT NULL,
+  "entity_id" uuid NOT NULL,
+  "category" varchar(100) NOT NULL,
+  "uploaded_by" uuid,
+  "created_at" timestamp with time zone NOT NULL DEFAULT now()
+);
+
+CREATE UNIQUE INDEX "file_company_path" ON "file" ("company_id", "path");
+CREATE INDEX "file_entity" ON "file" ("company_id", "entity_type", "entity_id");
+
+-- Update member_identifier: replace base64 columns with file references
+ALTER TABLE "member_identifier" DROP COLUMN IF EXISTS "image_front";
+ALTER TABLE "member_identifier" DROP COLUMN IF EXISTS "image_back";
+ALTER TABLE "member_identifier" DROP COLUMN IF EXISTS "image_front_url";
+ALTER TABLE "member_identifier" DROP COLUMN IF EXISTS "image_back_url";
+ALTER TABLE "member_identifier" ADD COLUMN "image_front_file_id" uuid REFERENCES "file"("id");
+ALTER TABLE "member_identifier" ADD COLUMN "image_back_file_id" uuid REFERENCES "file"("id");

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

@@ -85,6 +85,13 @@
       "when": 1774710000000,
       "tag": "0011_member_address",
       "breakpoints": true
+    },
+    {
+      "idx": 12,
+      "version": "7",
+      "when": 1774720000000,
+      "tag": "0012_file_storage",
+      "breakpoints": true
     }
   ]
 }