feat(gtm): add mandatory knowledge-base read/write directives to GTM skills

Agents must now read client profiles before GTM work and write session
logs after completing audits, tag changes, or validation — ensuring
findings compound across sessions instead of being lost.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/commands/gtm-validator.md

@@ -20,6 +20,20 @@ Priority reads per task:
 - "validate tags", "QA GTM", "debug GTM"
 - "naming conventions", "GTM best practice"
 
+## MANDATORY: Knowledge Base Read/Write
+
+**Before starting any validation or QA:**
+1. Identify the target client from container ID or URL
+2. Read `knowledge-base/accounts/<client>/profile.md` — naming conventions, known issues, platform stack
+3. Read `knowledge-base/accounts/<client>/*.md` — taxonomy defines expected events; naming fix plans reveal known violations
+4. Skim `knowledge-base/logs/<client>/` — past QA reveals recurring issues and known false positives
+
+**After completing validation, write a session log:**
+- Write to `knowledge-base/logs/<client>/YYYY-MM-DD-<description>.md`
+- Include: date, container ID, pass/fail results, broken triggers (IDs), new naming violations
+- Update `knowledge-base/accounts/<client>/profile.md` if you discovered persistent facts
+- See `AGENTS.md` for full format template
+
 ## Validation Modes
 
 ### 1. Tag Firing Verification