feat: delete task/account, edit endpoint, richer event log

- store: DeleteAccount, DeleteTask, UpdateEndpoint (+ cascade/update tests)
- httpapi: DELETE /tasks/{id}, DELETE /tasks/{id}/accounts/{accountId},
  PUT /endpoints/{id}; delete guarded with 409 while task running
- orchestrator: enrich WS events with login/host/port/error (test + run + errors)
- web: delete buttons (task, account) with confirm, endpoint edit form,
  human-readable event log (source/dest, host:port, error text)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMHQTtnQtQqL8muAXHr9kd

web/src/pages/Tasks.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState, type FormEvent } from 'react'
-import { createTask, listEndpoints, listTasks, type Endpoint, type Task } from '../api'
+import { createTask, deleteTask, listEndpoints, listTasks, type Endpoint, type Task } from '../api'
 import { StatusBadge } from '../components/StatusBadge'
 
 export function Tasks() {
@@ -22,6 +22,17 @@ export function Tasks() {
     listEndpoints().then((e) => setEndpoints(e ?? [])).catch(() => {})
   }, [])
 
+  async function onDeleteTask(id: number, taskName: string) {
+    if (!confirm(`Delete task "${taskName}" and all its accounts?`)) return
+    setError(null)
+    try {
+      await deleteTask(id)
+      reload()
+    } catch (e: unknown) {
+      setError(e instanceof Error ? e.message : 'Failed to delete task')
+    }
+  }
+
   async function submit(e: FormEvent) {
     e.preventDefault()
     setBusy(true)
@@ -118,16 +129,17 @@ export function Tasks() {
                 <th>Name</th>
                 <th>Route</th>
                 <th>Status</th>
+                <th></th>
               </tr>
             </thead>
             <tbody>
               {tasks === null ? (
                 <tr className="empty-row">
-                  <td colSpan={4}>loading…</td>
+                  <td colSpan={5}>loading…</td>
                 </tr>
               ) : tasks.length === 0 ? (
                 <tr className="empty-row">
-                  <td colSpan={4}>no tasks yet — create one above</td>
+                  <td colSpan={5}>no tasks yet — create one above</td>
                 </tr>
               ) : (
                 tasks.map((t) => (
@@ -144,6 +156,16 @@ export function Tasks() {
                     <td>
                       <StatusBadge status={t.status} />
                     </td>
+                    <td className="num-cell">
+                      <button
+                        type="button"
+                        className="link-btn danger"
+                        onClick={() => onDeleteTask(t.id, t.name)}
+                        disabled={t.status === 'running'}
+                      >
+                        delete
+                      </button>
+                    </td>
                   </tr>
                 ))
               )}