Fix notifications 500 (audit_id column), smart resolution time units

- notifications.php: audit_log PK is audit_id not log_id; alias all
  three queries with audit_id AS log_id to fix 500 error
- DashboardView: avg resolution time now picks best unit automatically
  (min < 1h, hr < 48h, days < 14d, wks otherwise) with full hours
  shown in title tooltip; adds lt-stat-unit CSS for the suffix

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/notifications.php

@@ -45,7 +45,7 @@ $myUsername = $currentUser['username'] ?? '';
 
 // Query 1: Tickets assigned to me (events from other users)
 $assignSql = "SELECT
-    al.log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
+    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
     COALESCE(u.display_name, u.username, 'System') AS actor_name
   FROM audit_log al
   LEFT JOIN users u ON al.user_id = u.user_id
@@ -88,7 +88,7 @@ $stmt->close();
 
 // Step B: fetch recent comment audit events not by the current user
 $commentSql = "SELECT
-    al.log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
+    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
     COALESCE(u.display_name, u.username, 'System') AS actor_name
   FROM audit_log al
   LEFT JOIN users u ON al.user_id = u.user_id
@@ -118,7 +118,7 @@ foreach ($rawCommentRows as $rawRow) {
 
 // Query 3: Status changes on watched tickets (from other users)
 $statusSql = "SELECT DISTINCT
-    al.log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
+    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
     COALESCE(u.display_name, u.username, 'System') AS actor_name
   FROM audit_log al
   LEFT JOIN users u ON al.user_id = u.user_id