fix: close all remaining known gaps across modules

Every 'read-only placeholder' and 'missing functionality' gap from the
QA audit is now resolved:

COURSES — categories/instructors/locations can now be deleted:
- Added update/delete methods to course-reference-data.service.ts
- Added deleteCategory/deleteInstructor/deleteLocation server actions
- Created DeleteRefDataButton client component with confirmation dialog
- Wired delete buttons into all three table pages

BOOKINGS — calendar month navigation now works:
- Calendar was hardcoded to current month with disabled prev/next
- Added year/month search params for server-side month rendering
- Replaced disabled buttons with Link-based navigation
- Verified: clicking next/prev correctly renders different months

DOCUMENTS — templates page now reads from database:
- Was hardcoded empty array; now queries document_templates table
- Table exists since migration 20260414000006_shared_templates.sql

FISCHEREI — statistics page shows real data:
- Replaced dashed-border placeholder with 6 real stat cards
- Queries waters, species, stocking, catch_books, leases, permits
- Shows counts + stocking costs + pending catch books
- Falls back to helpful message when no data exists

VERBAND — statistics page shows real KPIs:
- Added server-side data fetching (clubs, members, fees)
- Passes activeClubs, totalMembers, openFees as props
- Added 4 KPI cards: Aktive Vereine, Gesamtmitglieder,
  ∅ Mitglieder/Verein, Offene Beiträge
- Kept existing trend charts below KPI cards

apps/web/app/[locale]/home/[account]/courses/categories/page.tsx

@@ -2,6 +2,7 @@ import { FolderTree } from 'lucide-react';
 import { getTranslations } from 'next-intl/server';
 
 import { createCourseManagementApi } from '@kit/course-management/api';
+import { DeleteRefDataButton } from '@kit/course-management/components';
 import { getSupabaseServerClient } from '@kit/supabase/server-client';
 import { Card, CardContent, CardHeader, CardTitle } from '@kit/ui/card';
 
@@ -67,6 +68,7 @@ export default async function CategoriesPage({ params }: PageProps) {
                       <th scope="col" className="p-3 text-left font-medium">
                         {t('common.parent')}
                       </th>
+                      <th scope="col" className="w-16 p-3" />
                     </tr>
                   </thead>
                   <tbody>
@@ -80,6 +82,13 @@ export default async function CategoriesPage({ params }: PageProps) {
                           {String(cat.description ?? '—')}
                         </td>
                         <td className="p-3">{String(cat.parent_id ?? '—')}</td>
+                        <td className="p-3 text-right">
+                          <DeleteRefDataButton
+                            id={String(cat.id)}
+                            type="category"
+                            itemName={String(cat.name)}
+                          />
+                        </td>
                       </tr>
                     ))}
                   </tbody>

apps/web/app/[locale]/home/[account]/courses/instructors/page.tsx

@@ -2,6 +2,7 @@ import { GraduationCap } from 'lucide-react';
 import { getTranslations } from 'next-intl/server';
 
 import { createCourseManagementApi } from '@kit/course-management/api';
+import { DeleteRefDataButton } from '@kit/course-management/components';
 import { formatCurrencyAmount } from '@kit/shared/dates';
 import { getSupabaseServerClient } from '@kit/supabase/server-client';
 import { Card, CardContent, CardHeader, CardTitle } from '@kit/ui/card';
@@ -74,6 +75,7 @@ export default async function InstructorsPage({ params }: PageProps) {
                       <th scope="col" className="p-3 text-right font-medium">
                         {t('instructors.hourlyRate')}
                       </th>
+                      <th scope="col" className="w-16 p-3" />
                     </tr>
                   </thead>
                   <tbody>
@@ -96,6 +98,13 @@ export default async function InstructorsPage({ params }: PageProps) {
                             ? formatCurrencyAmount(inst.hourly_rate as number)
                             : '—'}
                         </td>
+                        <td className="p-3 text-right">
+                          <DeleteRefDataButton
+                            id={String(inst.id)}
+                            type="instructor"
+                            itemName={`${inst.first_name} ${inst.last_name}`}
+                          />
+                        </td>
                       </tr>
                     ))}
                   </tbody>

apps/web/app/[locale]/home/[account]/courses/locations/page.tsx

@@ -2,6 +2,7 @@ import { MapPin } from 'lucide-react';
 import { getTranslations } from 'next-intl/server';
 
 import { createCourseManagementApi } from '@kit/course-management/api';
+import { DeleteRefDataButton } from '@kit/course-management/components';
 import { getSupabaseServerClient } from '@kit/supabase/server-client';
 import { Card, CardContent, CardHeader, CardTitle } from '@kit/ui/card';
 
@@ -70,6 +71,7 @@ export default async function LocationsPage({ params }: PageProps) {
                       <th scope="col" className="p-3 text-right font-medium">
                         {t('list.capacity')}
                       </th>
+                      <th scope="col" className="w-16 p-3" />
                     </tr>
                   </thead>
                   <tbody>
@@ -89,6 +91,13 @@ export default async function LocationsPage({ params }: PageProps) {
                         <td className="p-3 text-right">
                           {String(loc.capacity ?? '—')}
                         </td>
+                        <td className="p-3 text-right">
+                          <DeleteRefDataButton
+                            id={String(loc.id)}
+                            type="location"
+                            itemName={String(loc.name)}
+                          />
+                        </td>
                       </tr>
                     ))}
                   </tbody>