Kanban：补齐看板事件、链接与批量操作闭环 (#634)

* feat(kanban): add board-scoped event stream bridge

* test(kanban): align event refresh expectation

* feat(kanban): add links and partial bulk bridge

* test(kanban): align links bulk refresh expectation

* fix(kanban): treat mutation stderr as failed

tests/server/kanban-routes.test.ts

@@ -9,6 +9,9 @@ const handlers = {
   assignees: vi.fn(async (ctx: any) => { ctx.body = { assignees: [] } }),
   readArtifact: vi.fn(async (ctx: any) => { ctx.body = { content: 'x' } }),
   searchSessions: vi.fn(async (ctx: any) => { ctx.body = { results: [] } }),
+  linkTasks: vi.fn(async (ctx: any) => { ctx.body = { ok: true } }),
+  unlinkTasks: vi.fn(async (ctx: any) => { ctx.body = { ok: true } }),
+  bulkUpdateTasks: vi.fn(async (ctx: any) => { ctx.body = { results: [] } }),
   list: vi.fn(async (ctx: any) => { ctx.body = { tasks: [] } }),
   get: vi.fn(async (ctx: any) => { ctx.body = { task: {} } }),
   create: vi.fn(async (ctx: any) => { ctx.body = { task: {} } }),
@@ -47,6 +50,8 @@ describe('kanban routes', () => {
       '/api/hermes/kanban/dispatch',
       '/api/hermes/kanban/artifact',
       '/api/hermes/kanban/search-sessions',
+      '/api/hermes/kanban/links',
+      '/api/hermes/kanban/tasks/bulk',
       '/api/hermes/kanban',
       '/api/hermes/kanban/:id',
       '/api/hermes/kanban/complete',