feat: add start-here master guide + enriched tool descriptions

Adds immutable "start-here" system guide as the master orientation doc
for agents. Enriches all tool descriptions with key rules at point of
use so agents can execute simple tasks without reading guides.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/mcp-server-standalone/services/guideService.js

@@ -18,6 +18,7 @@ const BUNDLED_USER_DIR = path.join(__dirname, '..', 'guides');
 
 // System guide names (immutable, always re-seeded)
 const SYSTEM_GUIDE_NAMES = new Set([
+  'start-here',
   'schema',
   'creating-nodes',
   'edges',