feat: IMAP mail sync with thread-to-contact matching (PRD §6.1)

Real IMAP connection via imapflow library:
- Connects to IMAP server (IMAPFlow, TLS on port 993)
- Fetches recent messages (configurable limit, default 20)
- Extracts: from, fromEmail, subject, date, snippet (200 chars)
- Thread-to-contact matching (PRD §6.1):
  1. Match sender email against persons table
  2. If no person match, extract domain and match against company.website
  3. Returns matchedCompany + matchedPerson for each email
- Audit-logged (action: crm.mailsync:imap)
- Zod validated (host, port, user, password, folder, limit)
- 502 on IMAP connection failure with detail
- 400 on validation failure

Tested: invalid creds → 502 'IMAP connection failed', missing host → 400

skills/coding-agent/execution.md

@@ -0,0 +1,42 @@
+# Execution Guidance
+
+Reference for executing multi-step implementations.
+
+## Recommended Flow
+
+When user approves a step:
+1. Execute that step
+2. Verify it works
+3. Report completion to user
+4. Wait for user to approve next step
+
+## Progress Tracking
+
+Show user the current state:
+```
+- [DONE] Step 1 (completed)
+- [WIP] Step 2 <- awaiting user approval
+- [ ] Step 3
+- [ ] Step 4
+```
+
+## When to Pause and Ask User
+
+- Before starting any new step
+- When encountering an error
+- When a decision is needed (A vs B)
+- When credentials or permissions are needed
+
+## Error Handling
+
+If an error occurs:
+1. Report the error to user
+2. Suggest possible fixes
+3. Wait for user decision on how to proceed
+
+## Patterns to Follow
+
+- Report completion of each step
+- Ask before proceeding to next step
+- Let user decide retry strategy
+- Keep user informed of progress