Phase 5: Add immutable file headers to all protected files

Added protection headers to 9 critical files:

JSON Files (x-immutable-notice field):
- .dss/schema/api.schema.json
- .dss/schema/tokens.schema.json
- .dss/schema/components.schema.json
- .dss/schema/workflows.schema.json
- .dss/schema/guardrails.schema.json
- dss-claude-plugin/.mcp.json

YAML File (comment header):
- .dss-boundaries.yaml

Markdown File (HTML comment):
- API_SPECIFICATION_IMMUTABLE.md

Python File (docstring header):
- dss-mvp1/dss/validators/schema.py

Each header includes:
- Protection notice
- Reason for immutability
- Last modified date
- Bypass instructions (DSS_IMMUTABLE_BYPASS=1)

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

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

.dss/schema/guardrails.schema.json

@@ -4,6 +4,12 @@
   "title": "DSS Guardrails Schema",
   "description": "AI boundary rules and enforcement policies",
   "version": "2.0.0",
+  "x-immutable-notice": {
+    "protected": true,
+    "reason": "Boundary enforcement policies - critical for AI guardrails integrity",
+    "lastModified": "2025-12-09",
+    "bypassMethod": "Use 'DSS_IMMUTABLE_BYPASS=1 git commit' or commit message '[IMMUTABLE-UPDATE] reason'"
+  },
   "type": "object",
   "required": ["immutableFiles", "boundaries", "tempFolderPolicy"],
   "properties": {