fix: harden CI validators, shell scripts, and expand test suite

- Add try-catch around readFileSync in validate-agents, validate-commands,
  validate-skills to handle TOCTOU races and file read errors
- Add validate-hooks.js and all test suites to package.json test script
  (was only running 4/5 validators and 0/4 test files)
- Fix shell variable injection in observe.sh: use os.environ instead of
  interpolating $timestamp/$OBSERVATIONS_FILE into Python string literals
- Fix $? always being 0 in start-observer.sh: capture exit code before
  conditional since `if !` inverts the status
- Add OLD_VERSION validation in release.sh and use pipe delimiter in sed
  to avoid issues with slash-containing values
- Add jq dependency check in evaluate-session.sh before parsing config
- Sync .cursor/ copies of all modified shell scripts

skills/continuous-learning/evaluate-session.sh

@@ -32,8 +32,12 @@ MIN_SESSION_LENGTH=10
 
 # Load config if exists
 if [ -f "$CONFIG_FILE" ]; then
-  MIN_SESSION_LENGTH=$(jq -r '.min_session_length // 10' "$CONFIG_FILE")
-  LEARNED_SKILLS_PATH=$(jq -r '.learned_skills_path // "~/.claude/skills/learned/"' "$CONFIG_FILE" | sed "s|~|$HOME|")
+  if ! command -v jq &>/dev/null; then
+    echo "[ContinuousLearning] jq is required to parse config.json but not installed, using defaults" >&2
+  else
+    MIN_SESSION_LENGTH=$(jq -r '.min_session_length // 10' "$CONFIG_FILE")
+    LEARNED_SKILLS_PATH=$(jq -r '.learned_skills_path // "~/.claude/skills/learned/"' "$CONFIG_FILE" | sed "s|~|$HOME|")
+  fi
 fi
 
 # Ensure learned skills directory exists