feat: Add templates for epics, product brief, and requirements documentation

- Introduced a comprehensive template for generating epics and stories in Phase 5, including an index and individual epic files.
- Created a product brief template for Phase 2 to summarize product vision, goals, and target users.
- Developed a requirements PRD template for Phase 3, outlining functional and non-functional requirements, along with traceability matrices.

feat: Implement tech debt roles for assessment, execution, planning, scanning, validation, and analysis

- Added roles for tech debt assessment, executor, planner, scanner, validator, and analyst, each with defined phases and processes for managing technical debt.
- Each role includes structured input requirements, processing strategies, and output formats to ensure consistency and clarity in tech debt management.

.claude/commands/ddd/scan.md

@@ -266,10 +266,39 @@ Write the index with code-first markers:
     "affectedComponents": ["tech-{slug}"],
     "relatedCommit": "full-hash",
     "timestamp": "ISO8601"
-  }]
+  }],
+  "freshness": {
+    "thresholds": { "warning": 0.3, "stale": 0.7 },
+    "weights": { "time": 0.1, "churn": 0.4, "symbol": 0.5 },
+    "time_decay_k": 0.05,
+    "auto_regenerate": false
+  },
+  "deepwiki_feature_to_symbol_index": {}
 }
 ```
 
+## Phase 6.5: Build DeepWiki Feature-to-Symbol Index
+
+If DeepWiki is available (`.codexlens/deepwiki_index.db` exists):
+
+1. Collect all `codeLocations[].path` from `technicalComponents[]`
+2. Query DeepWiki: `POST /api/deepwiki/symbols-for-paths { paths: [...] }`
+3. Build `deepwiki_feature_to_symbol_index` by traversing:
+   `feature → requirementIds → techComponentIds → codeLocations → symbols`
+
+```json
+"deepwiki_feature_to_symbol_index": {
+  "feat-auth": [
+    "deepwiki:symbol:src/auth/jwt.ts#L30-L55",
+    "deepwiki:symbol:src/models/user.ts#L12-L40"
+  ]
+}
+```
+
+**Symbol URN format**: `deepwiki:symbol:<file_path>#L<start>-L<end>`
+
+**Graceful degradation**: If DeepWiki is unavailable, set `deepwiki_feature_to_symbol_index: {}` and log warning.
+
 ## Phase 7: Generate Documents
 
 ### 7.1 Feature Maps