Admin-managed feedback categories

Categories move from a hard-coded list to a feedback_categories table
(migration 0062), seeded with the four existing keys, labels and
descriptions so production feedback is untouched; any other key already in
use gets an archived category. Keys are fixed, so renames relabel past
feedback. Archive hides a category from the form; only unused categories
can be deleted. Submissions are validated against active categories, and
feedback responses carry category_label.

New: GET /feedback/categories (public); /admin/feedback/categories CRUD +
reorder behind the new feedback:categories permission (granted to Admin).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/model/feedback.go

@@ -18,7 +18,10 @@ type Feedback struct {
 	ID           string     `json:"id"`
 	UserID       *string    `json:"user_id,omitempty"`
 	Category     string     `json:"category"`
-	Message      string     `json:"message"`
+	// CategoryLabel is the category's current display name (falls back to
+	// the key if the category was ever removed).
+	CategoryLabel string `json:"category_label"`
+	Message       string `json:"message"`
 	ContactEmail *string    `json:"contact_email,omitempty"`
 	CreatedAt    time.Time  `json:"created_at"`
 	// AcknowledgedAt is set when an admin presses "Acknowledge" on the
@@ -50,3 +53,15 @@ type Feedback struct {
 	AuthorName   *string `json:"author_name,omitempty"`
 	AuthorEmail  *string `json:"-"` // server-side only; never serialised
 }
+
+// FeedbackCategory is one option on the /feedback form, managed from the
+// admin panel. Key is what feedback.category stores and never changes.
+type FeedbackCategory struct {
+	Key         string     `json:"key"`
+	Label       string     `json:"label"`
+	Description string     `json:"description"`
+	SortOrder   int        `json:"sort_order"`
+	ArchivedAt  *time.Time `json:"archived_at,omitempty"`
+	// UsageCount is admin-only: how much feedback is filed under it.
+	UsageCount int `json:"usage_count,omitempty"`
+}