feat(store): TranscriptStatus read field + status setter/loader

Surfaces videos.transcript_status (migration 007) on SummaryRow and adds
SetTranscriptStatus / GetTranscriptStatus / RateLimitedVideoIDs.

SetTranscriptStatus is the single choke point for the rate-limit lifecycle:
"rate_limited" stamps rate_limited_at = NOW(), every other status clears it,
so the runner's backoff window and the UI badge read one consistent source.
RateLimitedVideoIDs is the per-pass loader (mirrors SeenVideoIDs) the runner
uses to skip still-throttled videos without re-hitting the caption endpoint.

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

internal/adapters/store/transcript_status_test.go

@@ -0,0 +1,80 @@
+package store_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"gitea.d-ma.be/mathias/tapir/internal/adapters/store"
+)
+
+func TestSetTranscriptStatus_RoundTrip(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	id, err := s.UpsertVideo(ctx, ytVideo(userA, "rt12345", "round trip"))
+	require.NoError(t, err)
+
+	// Unset by default.
+	got, err := s.GetTranscriptStatus(ctx, userA, id)
+	require.NoError(t, err)
+	require.Equal(t, "", got)
+
+	for _, status := range []string{"none", "fetched", "rate_limited", ""} {
+		require.NoError(t, s.SetTranscriptStatus(ctx, userA, id, status))
+		got, err := s.GetTranscriptStatus(ctx, userA, id)
+		require.NoError(t, err)
+		require.Equal(t, status, got)
+	}
+}
+
+func TestSetTranscriptStatus_RejectsInvalid(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	id, err := s.UpsertVideo(ctx, ytVideo(userA, "bad12345", "bad status"))
+	require.NoError(t, err)
+
+	require.Error(t, s.SetTranscriptStatus(ctx, userA, id, "bogus"))
+
+	// The rejected write left the status untouched.
+	got, err := s.GetTranscriptStatus(ctx, userA, id)
+	require.NoError(t, err)
+	require.Equal(t, "", got)
+}
+
+func TestSetTranscriptStatus_NotFound(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	require.ErrorIs(t, s.SetTranscriptStatus(ctx, userA, videoX, "fetched"), store.ErrNotFound)
+
+	_, err := s.GetTranscriptStatus(ctx, userA, videoX)
+	require.ErrorIs(t, err, store.ErrNotFound)
+}
+
+func TestRateLimitedVideoIDs_StampsAndClears(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	id, err := s.UpsertVideo(ctx, ytVideo(userA, "rl12345", "rate limited"))
+	require.NoError(t, err)
+
+	// Marking rate_limited stamps rate_limited_at, so the video appears.
+	require.NoError(t, s.SetTranscriptStatus(ctx, userA, id, "rate_limited"))
+	rl, err := s.RateLimitedVideoIDs(ctx, userA)
+	require.NoError(t, err)
+	require.Contains(t, rl, id)
+	require.False(t, rl[id].IsZero(), "rate_limited_at must be stamped")
+
+	// Moving off rate_limited clears the timestamp, so it drops out.
+	require.NoError(t, s.SetTranscriptStatus(ctx, userA, id, "fetched"))
+	rl, err = s.RateLimitedVideoIDs(ctx, userA)
+	require.NoError(t, err)
+	require.NotContains(t, rl, id)
+}