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/notify/notify_test.go

@@ -9,12 +9,12 @@ import (
 	"testing"
 )
 
-// TestShowRuftNotifySend: Auf Linux geht Show über notify-send — hier ein
-// Fake im PATH, der seine Argumente protokolliert (echter Prozess, kein
-// Mock-Framework). Titel und Text kommen unverändert an.
-func TestShowRuftNotifySend(t *testing.T) {
+// TestShowCallsNotifySend: on Linux, Show goes through notify-send; here a
+// fake in PATH that records its arguments (a real process, no mock
+// framework). Title and text arrive unchanged.
+func TestShowCallsNotifySend(t *testing.T) {
 	if runtime.GOOS != "linux" {
-		t.Skip("notify-send-Weg gibt es nur auf Linux")
+		t.Skip("the notify-send path exists only on Linux")
 	}
 	dir := t.TempDir()
 	seen := filepath.Join(dir, "seen.txt")
@@ -25,9 +25,9 @@ func TestShowRuftNotifySend(t *testing.T) {
 	t.Setenv("PATH", dir)
 
 	if !Available() {
-		t.Fatal("Available = false mit Fake im PATH")
+		t.Fatal("Available = false with fake in PATH")
 	}
-	if err := Show(context.Background(), "Ruhezeit: Build fertig"); err != nil {
+	if err := Show(context.Background(), "quiet hours: build done"); err != nil {
 		t.Fatalf("Show: %v", err)
 	}
 	b, err := os.ReadFile(seen)
@@ -35,27 +35,27 @@ func TestShowRuftNotifySend(t *testing.T) {
 		t.Fatal(err)
 	}
 	args := strings.Split(strings.TrimSpace(string(b)), "\n")
-	if args[len(args)-1] != "Ruhezeit: Build fertig" || args[len(args)-2] != Title {
-		t.Errorf("notify-send-Argumente = %q, want … %q %q", args, Title, "Ruhezeit: Build fertig")
+	if args[len(args)-1] != "quiet hours: build done" || args[len(args)-2] != Title {
+		t.Errorf("notify-send arguments = %q, want ... %q %q", args, Title, "quiet hours: build done")
 	}
 }
 
-// TestShowOhneWerkzeug: fehlt das Werkzeug, ist das ein klarer Fehler.
-func TestShowOhneWerkzeug(t *testing.T) {
+// TestShowWithoutTool: a missing tool is a clear error.
+func TestShowWithoutTool(t *testing.T) {
 	t.Setenv("PATH", t.TempDir())
 	if Available() {
-		t.Fatal("Available = true ohne Werkzeug")
+		t.Fatal("Available = true without tool")
 	}
 	if err := Show(context.Background(), "x"); err == nil {
-		t.Error("Show ohne Werkzeug: kein Fehler")
+		t.Error("Show without tool: no error")
 	}
-	if !strings.Contains(Describe(), "nicht gefunden") {
+	if !strings.Contains(Describe(), "not found") {
 		t.Errorf("Describe = %q", Describe())
 	}
 }
 
 func TestAppleString(t *testing.T) {
-	if got := appleString(`sag "hallo" \ tschüss`); got != `"sag \"hallo\" \\ tschüss"` {
+	if got := appleString(`say "hello" \ bye`); got != `"say \"hello\" \\ bye"` {
 		t.Errorf("appleString = %s", got)
 	}
 }