feat(coord): DB migration — project-scoped missions, multi-tenant RBAC

Closes #131

- Add userId, phase, milestones, config columns to missions table
- Add new mission_tasks table for coord-managed task tracking
- Both tables enforce per-user RBAC via userId foreign key
- Generate Drizzle migration (0001_magical_rattler.sql)
- Add userId-scoped query methods to brain missions repo
- Add new mission-tasks repo to brain package
- Extend CoordService with DB-backed mission and task CRUD
- Extend CoordController with DB-backed REST endpoints
- Preserve file-based coord endpoints for backwards compatibility

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

packages/db/drizzle/0001_magical_rattler.sql

@@ -0,0 +1,29 @@
+CREATE TABLE "mission_tasks" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"mission_id" uuid NOT NULL,
+	"task_id" uuid,
+	"user_id" text NOT NULL,
+	"status" text DEFAULT 'not-started' NOT NULL,
+	"description" text,
+	"notes" text,
+	"pr" text,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	"updated_at" timestamp with time zone DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+ALTER TABLE "missions" ADD COLUMN "user_id" text;--> statement-breakpoint
+ALTER TABLE "missions" ADD COLUMN "phase" text;--> statement-breakpoint
+ALTER TABLE "missions" ADD COLUMN "milestones" jsonb;--> statement-breakpoint
+ALTER TABLE "missions" ADD COLUMN "config" jsonb;--> statement-breakpoint
+ALTER TABLE "users" ADD COLUMN "banned" boolean DEFAULT false;--> statement-breakpoint
+ALTER TABLE "users" ADD COLUMN "ban_reason" text;--> statement-breakpoint
+ALTER TABLE "users" ADD COLUMN "ban_expires" timestamp with time zone;--> statement-breakpoint
+ALTER TABLE "mission_tasks" ADD CONSTRAINT "mission_tasks_mission_id_missions_id_fk" FOREIGN KEY ("mission_id") REFERENCES "public"."missions"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "mission_tasks" ADD CONSTRAINT "mission_tasks_task_id_tasks_id_fk" FOREIGN KEY ("task_id") REFERENCES "public"."tasks"("id") ON DELETE set null ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "mission_tasks" ADD CONSTRAINT "mission_tasks_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "mission_tasks_mission_id_idx" ON "mission_tasks" USING btree ("mission_id");--> statement-breakpoint
+CREATE INDEX "mission_tasks_task_id_idx" ON "mission_tasks" USING btree ("task_id");--> statement-breakpoint
+CREATE INDEX "mission_tasks_user_id_idx" ON "mission_tasks" USING btree ("user_id");--> statement-breakpoint
+CREATE INDEX "mission_tasks_status_idx" ON "mission_tasks" USING btree ("status");--> statement-breakpoint
+ALTER TABLE "missions" ADD CONSTRAINT "missions_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "missions_user_id_idx" ON "missions" USING btree ("user_id");