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/review-code.template.json

@@ -0,0 +1,14 @@
+{
+  "task_id": "TASK-0001",
+  "verdict": "pass",
+  "checked_guard_ids": [
+    "GR-CORE-003",
+    "GR-TEST-001"
+  ],
+  "checked_quality_gate_ids": [
+    "QG-001",
+    "QG-002",
+    "QG-003"
+  ],
+  "findings": []
+}