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/config/path.go

@@ -6,26 +6,25 @@ import (
 	"runtime"
 )
 
-// fileName ist der Name der Config-Datei im Config-Verzeichnis.
+// fileName is the config file's name inside the config directory.
 const fileName = "config.toml"
 
-// ErrNoHome meldet, dass das Heimatverzeichnis nicht bestimmt werden kann
-// (keine HOME- bzw. APPDATA-Umgebungsvariable).
-var ErrNoHome = errors.New("Config-Verzeichnis nicht bestimmbar (HOME bzw. APPDATA fehlt)")
+// ErrNoHome reports that the home directory cannot be determined (no HOME or
+// APPDATA environment variable).
+var ErrNoHome = errors.New("config directory unknown (HOME or APPDATA not set)")
 
-// Dir liefert das platform-native Config-Verzeichnis von talk auf dem
-// aktuellen System: Linux ~/.config/talk (respektive $XDG_CONFIG_HOME/talk),
-// macOS ~/Library/Application Support/talk, Windows %APPDATA%\talk.
+// Dir returns talk's platform-native config directory: ~/.config/talk on
+// Linux (or $XDG_CONFIG_HOME/talk), ~/Library/Application Support/talk on
+// macOS, %APPDATA%\talk on Windows.
 func Dir(getenv func(string) string) (string, error) {
 	return dirFor(runtime.GOOS, getenv)
 }
 
-// dirFor ist die testbare Plattformlogik hinter Dir: goos wird als
-// Parameter übergeben, damit die Pfade für alle Betriebssysteme vom
-// Dev-Host aus tischgesteuert geprüft werden können.
+// dirFor is the testable platform logic behind Dir: goos is a parameter so
+// all platforms can be table-tested from one host.
 //
-// XDG_CONFIG_HOME wird nur berücksichtigt, wenn es einen absoluten Pfad
-// enthält (XDG-Spezifikation); relative Werte werden ignoriert.
+// XDG_CONFIG_HOME is honoured only when it holds an absolute path (XDG
+// spec); relative values are ignored.
 func dirFor(goos string, getenv func(string) string) (string, error) {
 	if getenv == nil {
 		return "", ErrNoHome
@@ -43,7 +42,7 @@ func dirFor(goos string, getenv func(string) string) (string, error) {
 			return "", ErrNoHome
 		}
 		return filepath.Join(home, "Library", "Application Support", "talk"), nil
-	default: // linux und sonstige unixartige Systeme
+	default: // linux and other unix-likes
 		if xdg := getenv("XDG_CONFIG_HOME"); xdg != "" && filepath.IsAbs(xdg) {
 			return filepath.Join(xdg, "talk"), nil
 		}
@@ -55,8 +54,8 @@ func dirFor(goos string, getenv func(string) string) (string, error) {
 	}
 }
 
-// Path liefert den vollständigen Pfad der config.toml im platform-nativen
-// Config-Verzeichnis (Diagnose, Setup-Wizard).
+// Path returns the full path of config.toml in the config directory
+// (diagnostics, setup).
 func Path(getenv func(string) string) (string, error) {
 	dir, err := Dir(getenv)
 	if err != nil {