Add central configuration reference section

Reference ~/.secrets, ~/.hosts, and ~/.ssh/config for centralized
credentials and host management. Includes homelab-specific variables
for Syncthing, Home Assistant, n8n, and Cloudflare.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -390,6 +390,30 @@ git add -A && git commit -m "Update docs" && git push
 
 ---
 
+## Central Configuration Reference
+
+All homelab credentials and hosts are centralized in these files (synced via Syncthing):
+
+| File | Purpose | Usage |
+|------|---------|-------|
+| `~/.secrets` | API keys, tokens, credentials | `source ~/.secrets` then use `$VAR_NAME` |
+| `~/.hosts` | IPs, hostnames, service URLs | `source ~/.hosts` then use `$IP_*` or `$HOST_*` |
+| `~/.ssh/config` | SSH aliases for all homelab hosts | `ssh pve`, `ssh truenas`, `ssh docker-host`, etc. |
+
+**Key variables for homelab:**
+- `$SYNCTHING_API_KEY_*` - Syncthing API keys per device
+- `$HA_TOKEN` - Home Assistant long-lived access token
+- `$N8N_API_KEY` - n8n API key
+- `$CF_API_KEY` - Cloudflare API key for Traefik DNS
+- All SSH passwords: `$HUTSON_PC_PASS`, `$TRUENAS_PASS`, etc.
+
+**When adding new credentials or hosts:**
+1. Add to the central files (`~/.secrets` or `~/.hosts`)
+2. Files sync via Syncthing to all machines
+3. Update this CLAUDE.md if infrastructure changes
+
+---
+
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