docs(runbooks): add runbook spec, template, index and 6 first-batch runbooks; light-enhance existing 10

- RUNBOOKS.md: repo-level spec (six-field model, naming, safety, maturity path)
- runbooks/_template.md + README.md: standard template and 16-entry routing index
- new: issue-to-merge, fix-ci, release, rollback, network-change, network-recovery
- light-enhance 10 existing runbooks with Purpose/Scope/Safety headers
- AGENTS.md: point step 3 at index/spec, add runbook execution rules
- docs/agent-runbook-guide.md: archive of Manus AI guide

runbooks/mailcow-smtp-client.md

@@ -1,5 +1,14 @@
 # Runbook: use mailcow SMTP / IMAP (client)
 
+## Purpose
+
+Reference for configuring mail clients against the mailcow SMTP/IMAP endpoints.
+
+## Scope
+
+- Applicable: [mx2.windy.me](../hosts/mx2.windy.me.md) client submission (587/465) and IMAP/POP (993/995).
+- Not applicable: server-side mailcow configuration or administration.
+
 Target: [mx2.windy.me](../hosts/mx2.windy.me.md)  
 Prerequisite: a mailbox on `windy.me` (password from mailcow UI, not the admin account unless it is that mailbox).
 
@@ -52,3 +61,8 @@ Do not commit or paste real passwords into this repo.
 - Port/TLS mode mismatch (587 vs 465)
 - Account active in mailcow; not rate-limited / fail2banned after bad attempts
 - Apps that store SMTP in their own config (e.g. Vaultwarden `config.json`) may keep a **stale** password even when `.env` is correct — verify AUTH against the effective config ([vaultwarden-health](vaultwarden-health.md) §5)
+
+## Safety
+
+- Do not commit or paste real passwords into this repo or chat.
+- Use submission (587/465) for client sending; never use port 25 as a desktop/app outbound port.