refactor: relocate agent-system/ to .agents/ with 7-role workflow restructure

Moves the agent workflow system from agent-system/ to .agents/ (dotfile convention).
Restructured from 5-role to 7-role pipeline: adds Analyst and splits Reviewer into
Code Reviewer + Security Reviewer. Removes all old workflow run artifacts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.agents/templates/finalize.template.json

@@ -0,0 +1,12 @@
+{
+  "task_id": "TASK-0001",
+  "ready_to_finalize": false,
+  "code_review": "pass",
+  "security_review": "pass",
+  "acceptance_review": "pass",
+  "ci_status": "unknown",
+  "final_action": "hold",
+  "hold_reason": "Waiting for all three reviews and quality gates to pass.",
+  "commit_message": "",
+  "notes": ""
+}