fix(hooks): inline context in hooks.json, no bash scripts

SessionStart hook directly echoes context text instead of
calling external script. Simple, maintainable, no dependencies.

hooks/hooks.json

@@ -0,0 +1,11 @@
+{
+  "hooks": {
+    "SessionStart": [{
+      "matcher": "startup|resume|compact",
+      "hooks": [{
+        "type": "command",
+        "command": "echo 'EXTREMELY_IMPORTANT: hub-guide best-practice skills are loaded and active for this session. MANDATORY: engineering-principles, clean-code, clean-architecture, testing, error-handling, security, git-workflow, api-design. Use the Skill tool to load any hub-guide skill when its topic comes up. Never assume or guess -- always find evidence in the codebase or docs.'"
+      }]
+    }]
+  }
+}