feat(#136): build Completion Verification Engine

Implement verification engine to determine if AI agent work is truly
complete by analyzing outputs and detecting deferred work patterns.

Strategies:
- FileChangeStrategy: Detect TODO/FIXME, placeholders, stubs
- TestOutputStrategy: Validate pass rates, coverage (85%), skipped tests
- BuildOutputStrategy: Detect TS errors, ESLint errors, build failures

Deferred work detection patterns:
- "follow-up", "to be added later"
- "incremental improvement", "future enhancement"
- "TODO: complete", "placeholder implementation"
- "stub", "work in progress", "partially implemented"

Features:
- Confidence scoring (0-100%)
- Verdict system: complete/incomplete/needs-review
- Actionable suggestions for improvements
- Strategy-based extensibility

Integration:
- Complements Quality Orchestrator (#134)
- Uses Quality Gate Config (#135)

Tests: 46 passing with 95.27% coverage

Fixes #136

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/completion-verification/interfaces/index.ts

@@ -0,0 +1,2 @@
+export * from "./verification-context.interface";
+export * from "./verification-result.interface";

apps/api/src/completion-verification/interfaces/verification-context.interface.ts

@@ -0,0 +1,19 @@
+export interface VerificationContext {
+  taskId: string;
+  workspaceId: string;
+  agentId: string;
+  claimMessage: string;
+  filesChanged: string[];
+  outputLogs: string;
+  testResults?: TestResults;
+  buildOutput?: string;
+  previousAttempts: number;
+}
+
+export interface TestResults {
+  total: number;
+  passed: number;
+  failed: number;
+  skipped: number;
+  coverage?: number;
+}

apps/api/src/completion-verification/interfaces/verification-result.interface.ts

@@ -0,0 +1,27 @@
+export interface VerificationResult {
+  isComplete: boolean;
+  confidence: number; // 0-100
+  issues: VerificationIssue[];
+  suggestions: string[];
+  verdict: "complete" | "incomplete" | "needs-review";
+}
+
+export interface VerificationIssue {
+  type:
+    | "test-failure"
+    | "build-error"
+    | "missing-files"
+    | "low-coverage"
+    | "incomplete-implementation"
+    | "deferred-work";
+  severity: "error" | "warning" | "info";
+  message: string;
+  evidence?: string;
+}
+
+export interface StrategyResult {
+  strategyName: string;
+  passed: boolean;
+  confidence: number;
+  issues: VerificationIssue[];
+}