feat(web): honest, state-aware summarize status with charm spinner (ADR-025)

Clicking Summarize polled /status, which knew only "spinning" or "done". The web
ProcessVideo recorded an outcome only on success, so a 429'd or caption-less
click left transcript_status unset and the poll silently reverted to the
Summarize button — the rate limit was invisible and the click felt broken.

- ProcessVideo now records rate_limited / none / fetched (mirrors the runner); a
  rate-limited video keeps its requested flag so the background sweep retries it.
- /status is state-aware: summary card (done), working spinner (in-flight),
  a calm "waiting on rate limit, will retry" card that keeps polling so the
  summary lands on its own (no re-click), and a terminal "no captions" card.
- Charm status text (Claude-Code / Crush inspired): the spinner cycles playful
  tapir-themed gerunds via CSS only (no JS), decorative + an sr-only stable
  status line for a11y.

Pillar A (foreground fetch priority lane) is a separate follow-up.

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

internal/web/processing_handler_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/stretchr/testify/require"
 
 	"gitea.d-ma.be/mathias/tapir/internal/web"
@@ -129,3 +130,42 @@ func getStatus(t *testing.T, app *web.App, videoID string) *httptest.ResponseRec
 	app.Router().ServeHTTP(rec, req)
 	return rec
 }
+
+// setTranscriptStatus stamps videos.transcript_status directly (bypassing RLS via
+// the super pool) so a test can drive the status endpoint into a given state.
+func setTranscriptStatus(t *testing.T, p *pgxpool.Pool, videoID, status string) {
+	t.Helper()
+	_, err := p.Exec(context.Background(),
+		`UPDATE videos SET transcript_status = $2 WHERE id = $1`, videoID, status)
+	require.NoError(t, err)
+}
+
+// TestStatusRateLimitedShowsWaitingCard: a click that hit YouTube's rate limit
+// must surface the honest "waiting, will retry" card that keeps polling — not a
+// silent revert to the Summarize button.
+func TestStatusRateLimitedShowsWaitingCard(t *testing.T) {
+	app := newApp(t)
+	p := rawPool(t)
+	resetDB(t, p)
+	seedVideo(t, p, videoX, "Throttled Title", "https://x", time.Time{})
+	setTranscriptStatus(t, p, videoX, "rate_limited")
+
+	html := body(t, getStatus(t, app, videoX))
+	require.Contains(t, html, "Waiting on YouTube rate limits", "honest rate-limit copy")
+	require.Contains(t, html, `hx-trigger="every 30s"`, "waiting card keeps polling so it self-resolves")
+	require.NotContains(t, html, "Summarize this video", "must not revert to the Summarize button")
+}
+
+// TestStatusNoCaptionsTerminal: a no-captions outcome is terminal — an honest
+// message, no poll, no button to click back into the same dead end.
+func TestStatusNoCaptionsTerminal(t *testing.T) {
+	app := newApp(t)
+	p := rawPool(t)
+	resetDB(t, p)
+	seedVideo(t, p, videoX, "Silent Title", "https://x", time.Time{})
+	setTranscriptStatus(t, p, videoX, "none")
+
+	html := body(t, getStatus(t, app, videoX))
+	require.Contains(t, html, "No captions available", "honest terminal copy")
+	require.NotContains(t, html, "hx-trigger", "terminal card must stop polling")
+}