feat: duplicate link action, watcher migration, fulltext search migration

- CreateTicketView: "Link as duplicate" button on each duplicate result;
  stores chosen ticket ID in hidden field, auto-creates duplicates dependency
  after ticket is saved (TicketController)
- migrations/004: ticket_watchers table (ticket_id, user_id primary key)
- migrations/005: FULLTEXT index on tickets(title, description) for fast
  relevance search replacing LIKE scan

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

controllers/TicketController.php

@@ -125,6 +125,17 @@ class TicketController {
                     $GLOBALS['auditLog']->logTicketCreate($userId, $result['ticket_id'], $ticketData);
                 }
 
+                // Auto-link as duplicate if requested from create form
+                $linkDupOf = isset($_POST['link_duplicate_of']) ? (int)$_POST['link_duplicate_of'] : 0;
+                if ($linkDupOf > 0) {
+                    $depSql = "INSERT IGNORE INTO ticket_dependencies (ticket_id, depends_on_ticket_id, dependency_type, created_by)
+                               VALUES (?, ?, 'duplicates', ?)";
+                    $depStmt = $this->conn->prepare($depSql);
+                    $depStmt->bind_param("iii", $result['ticket_id'], $linkDupOf, $userId);
+                    $depStmt->execute();
+                    $depStmt->close();
+                }
+
                 // Send Matrix notification for new ticket
                 NotificationHelper::sendTicketNotification($result['ticket_id'], $ticketData, 'manual');
 

migrations/004_add_ticket_watchers.sql

@@ -0,0 +1,10 @@
+-- Migration: Add ticket watchers table
+-- Allows users to subscribe to ticket updates and receive Matrix notifications.
+
+CREATE TABLE IF NOT EXISTS ticket_watchers (
+    ticket_id  INT          NOT NULL,
+    user_id    INT          NOT NULL,
+    created_at TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (ticket_id, user_id),
+    INDEX idx_watcher_user (user_id)
+);

migrations/005_add_fulltext_search.sql

@@ -0,0 +1,6 @@
+-- Migration: Add FULLTEXT index on ticket title and description
+-- Replaces LIKE '%term%' with MATCH ... AGAINST for dramatically better search
+-- performance and relevance ranking at scale.
+-- MyISAM not needed — InnoDB supports FULLTEXT since MySQL 5.6.
+
+ALTER TABLE tickets ADD FULLTEXT INDEX ft_title_description (title, description);

views/CreateTicketView.php

@@ -37,6 +37,7 @@ include __DIR__ . '/layout_header.php';
 
   <input type="hidden" name="csrf_token"
          value="<?= htmlspecialchars(CsrfMiddleware::getToken(), ENT_QUOTES, 'UTF-8') ?>">
+  <input type="hidden" name="link_duplicate_of" id="linkDuplicateOf" value="">
 
   <?php if (isset($error)): ?>
   <div class="lt-msg lt-msg-danger lt-mb-md" role="alert">
@@ -269,6 +270,7 @@ include __DIR__ . '/layout_header.php';
                     ul.className = 'duplicate-list lt-text-sm';
                     data.duplicates.forEach(function (dup) {
                         var li   = document.createElement('li');
+                        li.className = 'lt-flex lt-flex-align-center lt-flex-gap-sm lt-mb-xs';
                         var a    = document.createElement('a');
                         a.href   = '/ticket/' + encodeURIComponent(dup.ticket_id);
                         a.target = '_blank';
@@ -277,14 +279,30 @@ include __DIR__ . '/layout_header.php';
                         var badge = document.createElement('span');
                         badge.className = 'lt-text-muted';
                         badge.textContent = '(' + dup.similarity + '% match, ' + dup.status + ')';
+                        var linkBtn = document.createElement('button');
+                        linkBtn.type = 'button';
+                        linkBtn.className = 'lt-btn lt-btn-ghost lt-btn-xs';
+                        linkBtn.dataset.dupId = dup.ticket_id;
+                        linkBtn.textContent = 'Link as duplicate';
+                        linkBtn.title = 'After creating, this ticket will be linked as a duplicate of #' + dup.ticket_id;
+                        linkBtn.addEventListener('click', function () {
+                            var chosen = this.dataset.dupId;
+                            document.getElementById('linkDuplicateOf').value = chosen;
+                            // Update all buttons to show current selection
+                            ul.querySelectorAll('[data-dup-id]').forEach(function (b) {
+                                b.textContent = b.dataset.dupId === chosen ? '\u2713 Will link' : 'Link as duplicate';
+                                b.classList.toggle('lt-btn-primary', b.dataset.dupId === chosen);
+                            });
+                        });
                         li.appendChild(a);
                         li.appendChild(dash);
                         li.appendChild(badge);
+                        li.appendChild(linkBtn);
                         ul.appendChild(li);
                     });
                     var hint = document.createElement('p');
                     hint.className = 'lt-text-xs lt-text-muted lt-mt-sm';
-                    hint.textContent = 'Check these before creating a new ticket.';
+                    hint.textContent = 'Check these before creating. Use "Link as duplicate" to auto-link after create.';
                     list.innerHTML = '';
                     list.appendChild(ul);
                     list.appendChild(hint);