feat(gns2): Gitea-Nervous-System v2.0 - distributed agent state machine

- Add GNS-2 label taxonomy (66 labels) with semantic routing
- Tier 2 agents (capability-analyst, agent-architect, evaluator) enabled for self-cascade
- GNS agent protocol: checkpoint v2 in issue body, machine-readable event footers
- GiteaClient extended: checkpoint CRUD, event parsing, assignee/lock control, triggered issue polling
- PipelineRunner rewritten as PollingSupervisor: reactive instead of active dispatch
- Security: circuit breakers (is_locked), budget governance, depth limits
- Scripts: init-gns-labels.py, validate-gns-agents.py
- Milestone #67 + 7 phase issues (#99-#105) tracking evolution

Refs: Milestone #67, Issues #99-#105

scripts/validate-gns-agents.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+"""
+GNS-2 Agent Protocol Validator
+Validates that agents follow Gitea-Nervous-System v2.0 protocol.
+"""
+import re
+import sys
+import yaml
+import glob
+
+CHECKPOINT_PATTERN = re.compile(r'## GNS Checkpoint\s*```yaml\s*(.*?)```', re.DOTALL)
+EVENT_PATTERN = re.compile(r'<!-- GNS_EVENT:\s*(.*?)\s*-->', re.DOTALL)
+
+def validate_agent_file(path):
+    with open(path) as f:
+        content = f.read()
+
+    errors = []
+    agent_name = path.split('/')[-1].replace('.md', '')
+
+    # Check frontmatter
+    if not content.startswith('---'):
+        errors.append('Missing YAML frontmatter')
+    else:
+        parts = content.split('---')
+        if len(parts) >= 2:
+            try:
+                fm = yaml.safe_load(parts[1])
+                if not fm.get('description'):
+                    errors.append('Missing description in frontmatter')
+                if 'mode' not in fm:
+                    errors.append('Missing mode in frontmatter')
+                if 'task' not in str(fm.get('permission', {})):
+                    errors.append('Missing task permission')
+            except Exception as e:
+                errors.append(f'Invalid YAML frontmatter: {e}')
+
+    # Check GNS protocol sections
+    if 'GNS Checkpoint' not in content:
+        errors.append('Missing GNS Checkpoint section')
+    if 'GNS_EVENT' not in content:
+        errors.append('Missing GNS_EVENT footer example')
+    if 'gns-agent-protocol' not in content.lower() and 'GNS' not in content:
+        errors.append('Agent not updated for GNS-2 protocol')
+
+    return errors
+
+def main():
+    print("GNS-2 Agent Protocol Validator")
+    print()
+
+    all_valid = True
+    for path in glob.glob('.kilo/agents/*.md'):
+        errors = validate_agent_file(path)
+        agent_name = path.split('/')[-1].replace('.md', '')
+
+        if errors:
+            print(f"❌ {agent_name}: {len(errors)} errors")
+            for err in errors:
+                print(f"   - {err}")
+            all_valid = False
+        else:
+            print(f"✅ {agent_name}")
+
+    print()
+    if all_valid:
+        print("All agents pass GNS-2 validation")
+        return 0
+    else:
+        print("Some agents need GNS-2 protocol update")
+        return 1
+
+if __name__ == '__main__':
+    sys.exit(main())