feat: create n8n workflow for secure log ingestion

Implement LogWhisperer_Ingest workflow for Sprint 2 Feature 2:

Workflow Components:
- Webhook trigger: POST /webhook/logwhisperer/ingest
- HMAC-SHA256 validation with timing-safe comparison
- Anti-replay protection (5min timestamp window)
- Data validation: UUID client_id, severity levels, non-empty logs
- PostgreSQL storage with logs table auto-creation
- Conditional routing for critical severity logs

Security Features:
- HMAC signature verification (X-LogWhisperer-Signature header)
- Timestamp validation preventing replay attacks
- Input sanitization before DB insert
- Environment variable LOGWHISPERER_SECRET for shared secret

Documentation:
- workflows/logwhisperer_ingest.json: Export JSON workflow
- workflows/README.md: Installation and usage guide
- workflows/INTEGRATION.md: Bash script integration guide
- workflows/REPORT.md: Implementation report
- workflows/test_workflow.sh: Automated test suite

Metodo Sacchi Applied:
- Safety First: HMAC validation before any processing
- Little Often: Modular nodes, each with single responsibility
- Double Check: Test suite validates all security requirements

Next Steps:
- Configure LOGWHISPERER_SECRET in n8n environment
- Import workflow to n8n instance
- Test end-to-end with secure_logwhisperer.sh

CHANGELOG.md

@@ -9,6 +9,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- feat: Create n8n workflow `LogWhisperer_Ingest` for secure log ingestion
+  - Webhook trigger on POST `/webhook/logwhisperer/ingest`
+  - HMAC-SHA256 signature validation with anti-replay protection
+  - Data validation (UUID, severity levels, non-empty raw_log)
+  - PostgreSQL storage with automatic table creation
+  - Conditional AI processing for critical severity logs
+  - JSON export at `workflows/logwhisperer_ingest.json`
+  - Test suite at `workflows/test_workflow.sh`
+  - Integration guide at `workflows/INTEGRATION.md`
+  - Documentation at `workflows/README.md`
+  - Implements Metodo Sacchi: Safety First, Little Often, Double Check
+
 - feat: Configure MCP servers for enhanced AI capabilities
   - sequential-thinking MCP for structured problem solving
   - context7 MCP for contextual library documentation retrieval