feat(security): implement template-based credential management for sensitive configurations

Introduce template-based approach to prevent credential exposure in version control.
This security enhancement establishes a standard pattern for managing sensitive data
across the homelab repository.

Changes:
- Create services/homepage/services.yaml.template with env var placeholders
  * Replace 7 hardcoded credentials with ${VARIABLE_NAME} format
  * Add OPNSense, Proxmox, Plex, Radarr, Sonarr, Deluge placeholders
- Create scripts/fix_n8n_db_c_locale.sh.template with env var validation
  * Remove hardcoded PostgreSQL password
  * Add N8N_DB_PASSWORD environment variable requirement
  * Include security reminder to shred script after use
- Update .gitignore with explicit exclusions for sensitive files
  * Add services/homepage/services.yaml exclusion
  * Add scripts/fix_n8n_db_c_locale.sh exclusion
- Create services/homepage/README.md with comprehensive setup guide
  * Document environment variable usage (recommended method)
  * Provide API key acquisition instructions for all services
  * Include troubleshooting and security best practices
- Update scripts/README.md with template pattern documentation
  * Add fix_n8n_db_c_locale.sh template usage instructions
  * Create "Template-Based Script Pattern" section
  * Enhance security guidelines with shred usage

Template Pattern Benefits:
- Repository remains credential-free
- Templates serve as documentation
- Easy to recreate configs on new systems
- Supports CI/CD pipelines with secret injection

Security Validation:
- No API keys in staged files (verified)
- No passwords in staged files (verified)
- .gitignore properly excludes sensitive files
- Templates contain clear usage instructions

Related: n8n troubleshooting (CLAUDE_STATUS.md), Docker Compose migration

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

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

.gitignore

@@ -122,6 +122,18 @@ services/**/*.db                # Database files
 services/**/*.sqlite            # SQLite database files
 services/**/*.sqlite3           # SQLite3 database files
 
+# Homepage Configuration (Sensitive)
+# ----------------------------------
+# Exclude the actual configuration file (contains API keys/passwords)
+# Template file (.template) is tracked for reference
+services/homepage/services.yaml
+
+# Operational Scripts (Sensitive)
+# -------------------------------
+# Exclude scripts with embedded credentials
+# Template files (.template) are tracked for reference
+scripts/fix_n8n_db_c_locale.sh
+
 # Custom Exclusions
 # ----------------
 # Add any custom patterns specific to your homelab below: