Add enterprise features: timeout handling, duration tracking, and health checking

- Add timeout handling to PHP syntax validation
- Add execution duration tracking to smoke_test and validate_all
- Create script_health.sh to validate enterprise standards compliance
- Enhance error messages with better context and actionable guidance
- Add log_duration helper function to common.sh
- Update ENTERPRISE.md and README.md with new features
- All scripts now follow complete enterprise standards

Co-authored-by: jmiller-moko <230051081+jmiller-moko@users.noreply.github.com>

scripts/validate/manifest.sh

@@ -35,6 +35,9 @@
 
 set -euo pipefail
 
+# Input validation
+SRC_DIR="${SRC_DIR:-src}"
+
 log() { printf '%s\n' "$*"; }
 
 fail() {
@@ -42,10 +45,14 @@ fail() {
   exit 1
 }
 
-SRC_DIR="${SRC_DIR:-src}"
-
+# Validate SRC_DIR
 if [ ! -d "${SRC_DIR}" ]; then
-  fail "${SRC_DIR} directory missing"
+  fail "${SRC_DIR} directory missing. Set SRC_DIR environment variable or ensure 'src' directory exists."
+fi
+
+# Validate required dependencies
+if ! command -v python3 >/dev/null 2>&1; then
+  fail "python3 is required but not found. Please install Python 3."
 fi
 
 # Candidate discovery policy: prefer explicit known names, otherwise fall back to extension-root manifests.