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-boundaries.yaml

@@ -1,3 +1,12 @@
+# ============================================================================
+# IMMUTABLE FILE - DO NOT MODIFY
+# ============================================================================
+# This file is protected by git pre-commit hooks.
+# Reason: Core boundary enforcement rules - critical for AI guardrails
+# Last Modified: 2025-12-09
+# To update: Use 'DSS_IMMUTABLE_BYPASS=1 git commit -m "[IMMUTABLE-UPDATE] reason"'
+# ============================================================================
+
 # DSS Boundary Configuration
 # This file defines what external APIs and operations are allowed
 # All AI interactions MUST go through DSS tools, not direct external access