feat: groupes de travail (P5)

Ajoute la notion de groupe — collection nommée de repos (membership légère
persistée, many-to-many) — pour piloter plusieurs repos en simultané :

- DB : migration #5 (tables groups + group_repos, FK ON DELETE CASCADE).
- GroupManager (synchrone, EventEmitter) + routes REST /api/v1/groups ;
  ne persiste que la membership, worktrees/sessions filtrés par repoId côté client.
- Protocole : GroupSummary, DTOs, topic WS « groups », events group_update/removed
  (additifs, PROTOCOL_VERSION inchangé).
- Web : store groups, GroupsListView, GroupView (réutilise RepoSection),
  grille multi-terminaux (TerminalGrid/TerminalCell), action « feature cross-repo »
  (orchestration client, tolérante aux échecs partiels), routes + i18n EN/FR.
- Tests : group-manager.test.ts + extension protocol.test.ts ; acceptance-p5.mjs.

packages/server/src/routes/groups.ts

@@ -0,0 +1,86 @@
+import type { FastifyInstance } from 'fastify';
+import type {
+  AddRepoRequest,
+  CreateGroupRequest,
+  GroupResponse,
+  GroupsListResponse,
+  UpdateGroupRequest,
+} from '@arboretum/shared';
+import type { GroupManager } from '../core/group-manager.js';
+import { sendManagerError } from './repos.js';
+
+export function registerGroupRoutes(app: FastifyInstance, gm: GroupManager): void {
+  app.get('/api/v1/groups', async (): Promise<GroupsListResponse> => ({ groups: gm.listGroups() }));
+
+  app.get('/api/v1/groups/:id', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    try {
+      return reply.send({ group: gm.getGroup(id) } satisfies GroupResponse);
+    } catch (err) {
+      return sendManagerError(reply, err);
+    }
+  });
+
+  app.post('/api/v1/groups', async (req, reply) => {
+    const body = req.body as Partial<CreateGroupRequest> | null;
+    if (!body || typeof body.label !== 'string') {
+      return reply.status(400).send({ error: { code: 'BAD_REQUEST', message: 'label is required' } });
+    }
+    try {
+      const group = gm.createGroup({
+        label: body.label,
+        ...(body.description !== undefined ? { description: body.description } : {}),
+        ...(body.color !== undefined ? { color: body.color } : {}),
+        ...(Array.isArray(body.repoIds) ? { repoIds: body.repoIds } : {}),
+      });
+      return reply.status(201).send({ group } satisfies GroupResponse);
+    } catch (err) {
+      return sendManagerError(reply, err);
+    }
+  });
+
+  app.patch('/api/v1/groups/:id', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    const body = (req.body as Partial<UpdateGroupRequest> | null) ?? {};
+    try {
+      const group = gm.updateGroup(id, {
+        ...(body.label !== undefined ? { label: body.label } : {}),
+        ...(body.description !== undefined ? { description: body.description } : {}),
+        ...(body.color !== undefined ? { color: body.color } : {}),
+      });
+      return reply.send({ group } satisfies GroupResponse);
+    } catch (err) {
+      return sendManagerError(reply, err);
+    }
+  });
+
+  app.delete('/api/v1/groups/:id', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    if (!gm.deleteGroup(id)) {
+      return reply.status(404).send({ error: { code: 'NOT_FOUND', message: 'No group with this id' } });
+    }
+    return reply.send({ ok: true });
+  });
+
+  app.post('/api/v1/groups/:id/repos', async (req, reply) => {
+    const { id } = req.params as { id: string };
+    const body = req.body as Partial<AddRepoRequest> | null;
+    if (!body || typeof body.repoId !== 'string') {
+      return reply.status(400).send({ error: { code: 'BAD_REQUEST', message: 'repoId is required' } });
+    }
+    try {
+      return reply.send({ group: gm.addRepo(id, body.repoId) } satisfies GroupResponse);
+    } catch (err) {
+      return sendManagerError(reply, err);
+    }
+  });
+
+  app.delete('/api/v1/groups/:id/repos/:repoId', async (req, reply) => {
+    const { id, repoId } = req.params as { id: string; repoId: string };
+    try {
+      return reply.send({ group: gm.removeRepo(id, repoId) } satisfies GroupResponse);
+    } catch (err) {
+      return sendManagerError(reply, err);
+    }
+  });
+}