fix: add MANDATORY prefix to all 8 core skill descriptions

- Add MANDATORY — always active to engineering-principles, testing,
  error-handling, security, git-workflow, api-design
- Update hook output with explicit EXTREMELY_IMPORTANT instruction
- Skills now explicitly state they apply to every session

hooks/scripts/detect-project.sh

@@ -42,8 +42,10 @@ MANDATORY="engineering-principles clean-code clean-architecture testing error-ha
 SKILL_NAMES="${SKILL_NAMES#, }"
 
 # --- output: plain text only, no emoji, no JSON ---
-echo "[hub-guide] detected: ${PROJECT_DIR}"
+echo "[hub-guide] session: ${PROJECT_DIR}"
 echo "[hub-guide] mandatory: ${MANDATORY}"
 if [ -n "$SKILL_NAMES" ]; then
   echo "[hub-guide] active: ${SKILL_NAMES}"
 fi
+echo ""
+echo "EXTREMELY_IMPORTANT: The hub-guide skills listed above are loaded and active. They apply to every code decision in this session. Never suppress lints. Never assume — show evidence. All skills work regardless of spoken language."