Add delete action for recurring templates

There was no way to remove a template once created (e.g. test/scratch
recurring tasks) - only edit/pause via active. DELETE /api/templates/:id
detaches any tasks already spawned from it (template_id cleared) rather
than blocking on the FK or cascading, so existing task history survives
as ordinary one-off tasks while the recurring schedule itself is removed.
Delete button in the edit modal footer, only shown when editing an
existing template - not on new/duplicate.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/Recurring.tsx

@@ -1,9 +1,9 @@
 import { Fragment, useCallback, useEffect, useMemo, useState } from 'react'
-import { Plus, X, Play, Copy, ChevronRight } from 'lucide-react'
+import { Plus, X, Play, Copy, ChevronRight, Trash2 } from 'lucide-react'
 import type { Template, TemplateGroup, Category, Location, Asset, Priority, ScheduleMode } from '../types'
 import { PRIORITIES, PRIORITY_LABELS, can } from '../types'
 import {
-  fetchTemplates, createTemplate, updateTemplate, runDueTemplates, fetchLocations, fetchAssets,
+  fetchTemplates, createTemplate, updateTemplate, deleteTemplate, runDueTemplates, fetchLocations, fetchAssets,
   fetchTemplateGroups, upsertTemplateGroup,
 } from '../api'
 import { useAuth } from '../components/AuthGate'
@@ -194,6 +194,18 @@ export default function Recurring() {
     }
   }
 
+  async function remove(id: number) {
+    if (!window.confirm('Delete this recurring template? Any tasks it already spawned stay in your history, but the schedule stops.')) return
+    try {
+      await deleteTemplate(id)
+      setForm(null)
+      setError(null)
+      load()
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Delete failed')
+    }
+  }
+
   function renderRow(t: Template) {
     return (
       <tr key={t.id} className={canManage ? 'clickable' : ''} onClick={() => openEdit(t)}>
@@ -399,6 +411,14 @@ export default function Recurring() {
               </label>
             )}
 
+            {form.id && (
+              <div className="modal-footer-actions">
+                <button className="btn-ghost-sm btn-ghost-danger" onClick={() => remove(form.id!)} title="Delete this recurring template">
+                  <Trash2 size={13} strokeWidth={1.75} /> Delete template
+                </button>
+              </div>
+            )}
+
             <div className="modal-actions">
               <button className="btn" onClick={() => setForm(null)}>Cancel</button>
               <button className="btn btn-primary" onClick={save}>Save</button>