docs(claude): require real UI/user-flow live validation (A4)

Per the F9 storage episode — live validation of a user-facing feature
must exercise the real flow end-to-end, not shortcut via direct
API/agent/CLI calls. Low-level mechanism tests are exempt.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -60,6 +60,10 @@ All shippable work commits **directly to `main`**; `main` is always equal to wha
 - Add debug capabilities (logging, verbose output) for easier troubleshooting
 - If you need more input or troubleshooting command output, ask first — don't guess
 
+## Live validation
+
+Live validation of a user-facing feature must exercise the real UI/user flow end-to-end (e.g. connect → enroll → deploy), not shortcut via direct API/agent/CLI calls — a shortcut can give false confidence and leave the system inconsistent (see the F9 storage episode). Low-level mechanism tests where the direct call IS the mechanism are exempt.
+
 ## Environment
 
 | Machine | OS | IP | Purpose |