feat(web): summarization-mode UI — all-videos list, Summarize queue, mode toggle

The list now shows ALL videos (ListVideos), not just summaries. Summarized cards
are unchanged; discovered-but-unsummarized videos render with a muted "pending"
treatment and either a "Summarize" button or a "Queued" chip.

- POST /v/{videoId}/summarize queues a video (RequestSummarize) and returns the
  refreshed card — it does NOT run the engine inline; `tapir run` is the single
  summarization driver, which picks up the flag on its next pass.
- Account page gains an Automatic/Manual toggle (POST /account/summarize-mode →
  SetAutoSummarize), shown as the current mode with a one-click switch.
- Both new POSTs degrade without JS (redirect back); HTMX swaps the fragment.

VideoCard and summarizeModeControl are extracted templ fragments reused as the
HTMX swap targets. views_templ.go regenerated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/web/account.go

@@ -28,7 +28,12 @@ func (a *App) handleAccount(w http.ResponseWriter, r *http.Request) {
 	if u, ok := a.Auth.CurrentUser(r); ok {
 		email = u.Email
 	}
-	a.render(w, r, AccountPage(name, email, conns, takeFlash(w, r)))
+	auto, err := a.Store.GetAutoSummarize(r.Context(), userID)
+	if err != nil {
+		a.serverError(w, r, "summarize mode", err)
+		return
+	}
+	a.render(w, r, AccountPage(name, email, conns, auto, takeFlash(w, r)))
 }
 
 // handleDisconnect removes a provider connection: it deletes the OAuth token from