refactor: switch the whole project to English

talk is going to be published. Code comments, CLI output, error messages,
daemon log lines, MCP descriptions and results, test names and assertions,
README, spec, skill, build scripts and flake are now English. Only the
spoken announcement texts stay bilingual: the wrap result and the test
sentence are German or English depending on the detected language.

Language fallback is now configurable: `lang = "en" | "de"` (env
TALK_LANG, default en) is used when detection cannot tell (numbers, single
words, ties) and for talk's own announcements. langdetect.Detect takes the
fallback as an argument instead of hard-coding German. `talk setup` asks for
it; `talk doctor` and `talk status` show it.

Vocabulary pinned across packages so the process-boundary tests observe
stable strings: chain log lines ("chain: tier X skipped (not available)",
"falling back to the next tier", "spoken via X"), queue lines ("discarded:
quiet hours ... active", "replaced by toast", "max_age"), CLI notes
("speaking directly", "daemon started at", "no daemon", "nothing to cancel"),
status block with aligned English labels, MCP messages, origin guard 403.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/audio/check.go

@@ -6,11 +6,11 @@ import (
 	"time"
 )
 
-// Check prüft, ob der Sink name einsatzbereit ist, ohne Ton zu erzeugen:
-// null ist immer bereit; oto initialisiert den Audio-Kontext (Standard-
-// Format 44,1 kHz Stereo 16 Bit) und wartet auf dessen Bereitschaft — so
-// fällt „kein Audiogerät" (Server, Container, fehlende PulseAudio/ALSA-
-// Bibliothek) in `talk doctor` auf, nicht erst bei der ersten Ansage.
+// Check verifies that the sink name is ready without producing sound: null
+// is always ready; oto initializes the audio context (default format 44.1
+// kHz stereo 16 bit) and waits for it to become ready, so "no audio device"
+// (servers, containers, missing PulseAudio/ALSA library) shows up in
+// `talk doctor` rather than at the first announcement.
 func Check(ctx context.Context, name string) error {
 	switch name {
 	case NameNull:
@@ -23,15 +23,15 @@ func Check(ctx context.Context, name string) error {
 		select {
 		case <-c.ready:
 			if err := c.ctx.Err(); err != nil {
-				return fmt.Errorf("oto: Initialisierung fehlgeschlagen: %w", err)
+				return fmt.Errorf("oto: initialization failed: %w", err)
 			}
 			return nil
 		case <-ctx.Done():
-			return fmt.Errorf("oto: Audio-Gerät antwortet nicht (%v)", ctx.Err())
+			return fmt.Errorf("oto: audio device not responding (%v)", ctx.Err())
 		case <-time.After(5 * time.Second):
-			return fmt.Errorf("oto: Audio-Gerät antwortet nicht binnen 5 s")
+			return fmt.Errorf("oto: audio device not responding within 5 s")
 		}
 	default:
-		return fmt.Errorf("unbekannter audio sink %q (erlaubt: %q, %q)", name, NameOto, NameNull)
+		return fmt.Errorf("unknown audio sink %q (allowed: %q, %q)", name, NameOto, NameNull)
 	}
 }