feat(models+gate): 模型按项目可配置(默认 opus-4.8) + diff 声明外文件硬闸

① 模型可配置（项目维度，默认 opus-4.8）
- 新增 projects.models（JSON，按角色 executor/planner/reviewer/conflict
  覆盖，值可为字符串=全复杂度统一 或 {easy,medium,hard} 分档）
- models.ts 重构 resolveModel：优先级 项目级 models > 旧 project.model
  (仅 executor/planner) > env > 默认 DEFAULT_MODEL(opus-4.8)
- 取消内置 fable/sonnet 分档默认：所有角色默认 opus-4.8（彻底回避 fable-5
  不可用问题，需要时项目级显式配置即可）；回退链改 opus→sonnet→fable
- API PATCH /projects 透传 models；sanitizeModels 落库校验

② diff 声明外文件闸（task.scopeFiles）
- 新增 tasks.scope_files（JSON glob/路径数组）
- checks.ts: globToRegExp/matchesAnyGlob + scopeFileGate（改动文件越界=硬闸，
  空声明跳过，git 出错不拦截）；pipeline runApproveGates 接入
- planner 拆解新增每子任务 files 字段：prompt 要求 + parseDecompose 解析 +
  ingest 落 scopeFiles，自动填充声明范围
- executor prompt 注入「声明文件范围约束」，让 agent 知边界（gate 才公平）

迁移：projects.models / tasks.scope_files 走 ensureColumn 幂等迁移（旧库补列）
测试：models 默认/配置/优先级、scope glob/gate、planner files 解析、
      store 持久化往返、迁移补列 —— 237 通过

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/api/server.ts

@@ -101,6 +101,7 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     if (b.autoApproveExec !== undefined) patch.autoApproveExec = Boolean(b.autoApproveExec);
     if (b.checks !== undefined) patch.checks = b.checks === null || b.checks === '' ? null : String(b.checks);
     if (b.agentRules !== undefined) patch.agentRules = b.agentRules === null || b.agentRules === '' ? null : String(b.agentRules);
+    if (b.models !== undefined) patch.models = b.models === null || b.models === '' ? null : (b.models as PatchProjectInput['models']);
     return projectOut(store.patchProject(id, patch));
   });
 
@@ -216,6 +217,7 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
       parentId: b.parentId ? String(b.parentId) : null,
       priority: b.priority === undefined ? undefined : Number(b.priority),
       deps: Array.isArray(b.deps) ? (b.deps as string[]) : undefined,
+      scopeFiles: Array.isArray(b.scopeFiles) ? (b.scopeFiles as string[]) : undefined,
     });
     if (auto) {
       // 异步分类回填：classifyComplexity 自身永不抛错（失败兜底 medium），外层再兜一层防御
@@ -293,6 +295,12 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
       }
       patch.deps = b.deps as string[];
     }
+    if (b.scopeFiles !== undefined) {
+      if (b.scopeFiles !== null && (!Array.isArray(b.scopeFiles) || !b.scopeFiles.every((f) => typeof f === 'string'))) {
+        throw new StoreError('scopeFiles 必须是文件 glob 字符串数组或 null');
+      }
+      patch.scopeFiles = b.scopeFiles as string[] | null;
+    }
     return store.patchTask(id, patch);
   });