fix(alias): answer inline queries from one store read under a deadline

Telegram expires an inline query and then rejects the answer with "query
is too old and response timeout expired or query ID is invalid". The
picker invited that: it listed the names and then read the store once per
name — up to 50 round trips per keystroke — and it was the only handler
in the module with no deadline of its own. Updates are dispatched one at
a time, so a single slow answer also held up the queries queued behind
it, each ageing while it waited, and one slow read expired a whole burst
of typing.

Add DocStore.Scan, which reads a key prefix with its values in one round
trip, ordered by key. The picker and /aliases both use it, so neither
grows a round trip per saved alias. Bound the inline handler at 3s: an
answer later than that is rejected anyway, and giving up frees the worker
for the fresher query behind it. When Telegram does reject an answer, the
error now carries how long it took, which separates a slow handler from a
query that was already stale on arrival.

The 50-result cap now counts results the picker can show, so a video-note
alias — which has no cached inline type — no longer consumes a slot.

internal/modules/alias/alias_inline_test.go

@@ -181,3 +181,25 @@ func TestInline_CapsAtFiftyResults(t *testing.T) {
 func uniqueName(i int) string {
 	return "n" + strings.Repeat("x", i/10) + string(rune('a'+i%10))
 }
+
+// The cap counts results the picker can actually show. A kind with no cached
+// inline type must not consume a slot, or a handful of video notes would
+// shrink an otherwise full answer.
+func TestInline_VideoNotesDoNotConsumeCapSlots(t *testing.T) {
+	rb := installAlias(t)
+	for i := 0; i < 10; i++ {
+		rb.Bot.ProcessUpdate(context.Background(),
+			aliasCmd(uniqueName(i), &models.Message{VideoNote: &models.VideoNote{FileID: "note-id"}}))
+	}
+	for i := 10; i < 70; i++ {
+		rb.Bot.ProcessUpdate(context.Background(),
+			aliasCmd(uniqueName(i), &models.Message{Text: "x"}))
+	}
+
+	rb.Reset()
+	rb.Bot.ProcessUpdate(context.Background(), inlineQuery(7, ""))
+
+	if got := len(inlineResults(t, rb)); got != 50 {
+		t.Errorf("returned %d results, want the full 50 despite the skipped video notes", got)
+	}
+}