feat(header): add smart sticky scroll animation and styling refinements

- Implement RAF-throttled smart sticky scroll interaction on app header
- Add flow-root BFC isolation, vertical margin, and mobile menu scroll container
- Update brand logo kicker hover color to primary accent (cobalt-dark)
- Fix theme script hydration warning with suppressHydrationWarning
- Add favicon.ico and icon.svg to resolve root /favicon.ico 404
- Add MAM orchestration guidelines, env generation script, and templates

.gitignore

@@ -6,4 +6,15 @@
 .agents/
 
 # Binary zip archives
-*.zip
+*.zip
+# >>> MAM managed block (managed by install.sh — do not edit) >>>
+/.venv/
+/.mam/
+/.mam_deploy/
+/.mam.env
+/.mam.env.*
+!/.mam.env.example
+/.cache/multi-agent-mux-monitor/
+/.mam-skill-backup.*/
+CURRENT_JOB.md
+# <<< MAM managed block <<<