fix: use local-time Date constructor in session-manager to prevent timezone day shift

new Date('YYYY-MM-DD') creates UTC midnight, which in negative UTC offset
timezones (e.g., Hawaii) causes getDate() to return the previous day.
Replaced with new Date(year, month - 1, day) for correct local-time behavior.

Added 15 tests: session-manager datetime verification and edge cases (7),
package-manager getCommandPattern special characters (4), and
validators model/skill-reference validation (4). Tests: 651 → 666.

scripts/lib/session-manager.js

@@ -47,8 +47,10 @@ function parseSessionFilename(filename) {
     filename,
     shortId,
     date: dateStr,
-    // Convert date string to Date object
-    datetime: new Date(dateStr)
+    // Use local-time constructor (consistent with validation on line 40)
+    // new Date(dateStr) interprets YYYY-MM-DD as UTC midnight which shows
+    // as the previous day in negative UTC offset timezones
+    datetime: new Date(year, month - 1, day)
   };
 }