feat(dashboards): resumable chat across navigation/reload + editable Source view

Generation state (chat, streaming steps, the built config) moves out of
DashboardWorkspace's component-local useState into a new
useDashboardChatStore, keyed by dashboard id (or new:<connectionId> before
the first save, with an alias/rekey scheme for the transition). Navigating
away no longer aborts the in-flight SSE stream, and on mount, if the
persisted dashboard's generationStatus is RUNNING (a turn was in flight
when this tab wasn't around, per the paired backend commit), the store
polls until it resolves instead of assuming nothing is happening.

Also adds:
- A Source/Preview toggle with an uncontrolled Monaco HTML editor
  (defaultValue + remount key, not a controlled value — a controlled value
  rewrites Monaco's model on every keystroke, resetting the caret mid-word).
  Apply re-derives the dashboard's title from the edited <title>/<h1> so a
  manual rename actually propagates to the breadcrumb/gallery, and is
  disabled while a generation is in flight to avoid racing the backend's
  own write of the same config.
- A Queries panel: DashboardArtifact now reports every query the artifact
  runs (SQL, row count or error, timing) via a new onQuery prop, wired to a
  side panel with copy-to-clipboard. dashboardQueryAPI.run now surfaces the
  backend's actual error message instead of axios's generic "Request failed
  with status code 400" (the interceptor only reads response.data.message;
  this endpoint's payload uses `error`).
- generateStream's fetch is aborted proactively on the page's `pagehide`
  event and the resulting failure is dropped rather than surfaced as a
  chat-history error: a reload/close tears down the request as a bare
  TypeError, indistinguishable in shape from a dead backend, which would
  otherwise get permanently written into the saved chat on every reopen.

Author: notSumit25

src/components/DashboardArtifact.jsx

@@ -97,7 +97,7 @@ const sleep = (ms) => new Promise((r) => setTimeout(r, ms))
 const REDUCED_MOTION = typeof window !== 'undefined'
   && window.matchMedia?.('(prefers-reduced-motion: reduce)').matches
 
-export default function DashboardArtifact({ connectionId, html, onError, queryFn }) {
+export default function DashboardArtifact({ connectionId, html, onError, queryFn, onQuery }) {
   const iframeRef = useRef(null)
   const [height, setHeight] = useState(600)
   const [loaded, setLoaded] = useState(false)
@@ -111,6 +111,12 @@ export default function DashboardArtifact({ connectionId, html, onError, queryFn
   const runQueryRef = useRef(null)
   runQueryRef.current = queryFn || ((sql, limit, signal) => dashboardQueryAPI.run(connectionId, sql, limit, signal))
 
+  // Log every query the artifact runs (SQL, row count, timing) for the
+  // Queries panel — same ref-indirection as runQueryRef, since pump/runJob's
+  // closures are frozen at first render (empty-dep useCallback).
+  const onQueryRef = useRef(null)
+  onQueryRef.current = onQuery
+
   function post(msg) {
     iframeRef.current?.contentWindow?.postMessage(msg, '*')
   }
@@ -124,13 +130,18 @@ export default function DashboardArtifact({ connectionId, html, onError, queryFn
   }, [])
 
   async function runJob(job) {
+    const startedAt = Date.now()
     for (let attempt = 0; ; attempt += 1) {
       const controller = new AbortController()
       const timer = setTimeout(() => controller.abort(), QUERY_TIMEOUT_MS)
       try {
         const res = await runQueryRef.current(job.sql, job.limit, controller.signal)
         clearTimeout(timer)
         post({ __deepsql: true, type: 'result', id: job.id, columns: res.columns, rows: res.rows })
+        onQueryRef.current?.({
+          id: job.id, sql: job.sql, status: 'success',
+          rowCount: res.rows?.length || 0, durationMs: Date.now() - startedAt, timestamp: startedAt,
+        })
         return
       } catch (err) {
         clearTimeout(timer)
@@ -142,9 +153,11 @@ export default function DashboardArtifact({ connectionId, html, onError, queryFn
           await sleep(400 * (attempt + 1) + Math.floor(Math.random() * 250))
           continue
         }
-        post({
-          __deepsql: true, type: 'result', id: job.id,
-          error: timedOut ? 'Timed out' : (err?.message || 'query failed'),
+        const errorMsg = timedOut ? 'Timed out' : (err?.message || 'query failed')
+        post({ __deepsql: true, type: 'result', id: job.id, error: errorMsg })
+        onQueryRef.current?.({
+          id: job.id, sql: job.sql, status: 'error',
+          rowCount: 0, durationMs: Date.now() - startedAt, timestamp: startedAt, error: errorMsg,
         })
         return
       }