refactor(issue): unify solution ID format to SOL-{issue-id}-{seq}

- Update solution-schema.json pattern to support new format
- Add Solution ID Format specification to plan.md
- Fix JSON parsing with extractJsonFromMarkdown + try-catch
- Update all examples in agent and prompt files:
  - issue-plan-agent.md
  - issue-queue-agent.md
  - issue-execute.md
  - issue-queue.md
  - queue.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.codex/prompts/issue-queue.md

@@ -78,8 +78,8 @@ Build a file → solutions mapping:
 
 ```javascript
 fileModifications = {
-  "src/auth.ts": ["SOL-001", "SOL-003"],
-  "src/api.ts": ["SOL-002"]
+  "src/auth.ts": ["SOL-ISS-001-1", "SOL-ISS-003-1"],
+  "src/api.ts": ["SOL-ISS-002-1"]
 }
 ```
 
@@ -129,7 +129,7 @@ Group assignment:
     {
       "item_id": "S-1",
       "issue_id": "ISS-001",
-      "solution_id": "SOL-001",
+      "solution_id": "SOL-ISS-001-1",
       "status": "pending",
       "execution_order": 1,
       "execution_group": "P1",