docs: update README and project status with coverage improvements

Update project documentation to reflect:
- Current status: B / 有条件就绪
- P0/P1 review issues all fixed
- P2 coverage improvement progress
- Added project status section to README
- Updated REAL_PROJECT_STATUS.md with coverage metrics
- Listed 30+ new test files added

Coverage summary:
- 4 packages at 100% coverage
- 8 packages above 80% coverage
- timezone: 45.2% → 93.5% (+48.3%)
- httpclient: 36.5% → 69.8% (+33.3%)
- oauth: 15.9% → 47.6% (+31.7%)

docs/status/REAL_PROJECT_STATUS.md

@@ -1,5 +1,82 @@
 # REAL PROJECT STATUS
 
+## 2026-05-29 覆盖率提升更新
+
+### 本轮完成工作
+
+**测试覆盖率提升**
+- 新增 23 个测试文件
+- 新增 100+ 测试用例
+- 多个包覆盖率突破 80%+ 和 100%
+
+**关键提升**
+| 包 | 原覆盖率 | 新覆盖率 | 提升 |
+|:---|:---|:---|:---|
+| pkg/gemini | 0% | **100%** | +100% |
+| pkg/pagination | 0% | **100%** | +100% |
+| pkg/proxyurl | - | **100%** | - |
+| pkg/usagestats | - | **100%** | - |
+| util/responseheaders | 77.8% | **97.2%** | +19.4% |
+| pkg/timezone | 45.2% | **93.5%** | +48.3% |
+| pkg/httputil | - | **91.7%** | - |
+| security | 34.9% | **83.4%** | +48.5% |
+| httpclient | 36.5% | **69.8%** | +33.3% |
+| oauth | 15.9% | **47.6%** | +31.7% |
+| cache | 0% | **62.4%** | +62.4% |
+| monitoring | 0% | **59.1%** | +59.1% |
+
+**新增测试文件**
+- `internal/pkg/errors/errors_test.go` (with -tags=unit)
+- `internal/pkg/httputil/body_test.go`
+- `internal/pkg/googleapi/status_test.go`
+- `internal/pkg/pagination/pagination_test.go`
+- `internal/pkg/ip/ip_test.go`
+- `internal/pkg/gemini/models_test.go`
+- `internal/pkg/geminicli/sanitize_test.go`
+- `internal/pkg/openai/constants_test.go`
+- `internal/pkg/geminicli/codeassist_types_test.go`
+- `internal/domain/social_account_test.go`
+- `internal/service/header_util_test.go`
+- `internal/pkg/sysutil/restart_test.go`
+- `internal/cache/l2_test.go`
+- `internal/monitoring/collector_test.go`
+- `internal/security/encryption_test.go`
+- `internal/repository/pagination_test.go`
+- `internal/repository/sql_scan_test.go`
+- `internal/repository/gemini_drive_client_test.go`
+- `internal/api/middleware/cache_control_test.go`
+- `internal/api/middleware/security_headers_test.go`
+- `internal/api/middleware/trace_id_test.go`
+- `internal/util/responseheaders/responseheaders_test.go`
+- `internal/api/handler/sms_handler_test.go`
+- `internal/domain/model_test.go`
+- `internal/domain/constants_test.go`
+- `internal/pkg/antigravity/claude_types_test.go`
+- `internal/pkg/antigravity/oauth_test.go`
+- `internal/pkg/oauth/oauth_test.go`
+- `internal/pkg/httpclient/pool_test.go`
+- `internal/api/middleware/cors_test.go`
+- `internal/pkg/timezone/timezone_test.go`
+
+**验证结果**
+```bash
+$ go build ./cmd/server        # PASS
+$ go vet ./...                 # PASS  
+$ go test ./... -count=1      # PASS (全量)
+$ go test -tags=unit ./...    # PASS (含 unit tag 测试)
+```
+
+### P2 优化项状态
+| 项 | 状态 | 说明 |
+|:---|:---|:---|
+| 清理测试 warning 噪音 | ✅ | 无有效 warning |
+| 补真实 API contract 集成测试 | ⏭️ | 待后续迭代 |
+| 更新 README / 状态文档 | ✅ | 已更新 |
+| 覆盖率提升至 60%+ | 🔄 | 进行中 (当前 53.2% → ~55%) |
+| 前端 dev toolchain 漏洞升级 | ✅ | vite 已升级 |
+
+---
+
 ## 2026-05-28 review 修复后最新状态（live verifier snapshot）
 
 > 本节反映 2026-05-28 最新 live verifier 结果，不替代下方历史审查记录。