feat: add project_goals many-to-many join table

Create project_goals join table with composite PK (project_id, goal_id),
backfill from existing projects.goal_id, and update the project service
to read/write through the join table. Shared types now include goalIds
and goals arrays on Project. Legacy goalId column is kept in sync.

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

packages/db/src/schema/index.ts

@@ -6,6 +6,7 @@ export { agentRuntimeState } from "./agent_runtime_state.js";
 export { agentTaskSessions } from "./agent_task_sessions.js";
 export { agentWakeupRequests } from "./agent_wakeup_requests.js";
 export { projects } from "./projects.js";
+export { projectGoals } from "./project_goals.js";
 export { goals } from "./goals.js";
 export { issues } from "./issues.js";
 export { issueApprovals } from "./issue_approvals.js";

packages/db/src/schema/project_goals.ts

@@ -0,0 +1,21 @@
+import { pgTable, uuid, timestamp, index, primaryKey } from "drizzle-orm/pg-core";
+import { companies } from "./companies.js";
+import { projects } from "./projects.js";
+import { goals } from "./goals.js";
+
+export const projectGoals = pgTable(
+  "project_goals",
+  {
+    projectId: uuid("project_id").notNull().references(() => projects.id, { onDelete: "cascade" }),
+    goalId: uuid("goal_id").notNull().references(() => goals.id, { onDelete: "cascade" }),
+    companyId: uuid("company_id").notNull().references(() => companies.id),
+    createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
+    updatedAt: timestamp("updated_at", { withTimezone: true }).notNull().defaultNow(),
+  },
+  (table) => ({
+    pk: primaryKey({ columns: [table.projectId, table.goalId] }),
+    projectIdx: index("project_goals_project_idx").on(table.projectId),
+    goalIdx: index("project_goals_goal_idx").on(table.goalId),
+    companyIdx: index("project_goals_company_idx").on(table.companyId),
+  }),
+);