fix: deepen opens the linked note, task list columns in "Alle Aufgaben", Whisper repeats, date field

- The deepen buttons of task rows and Kanban cards open an already linked note (accent colour)
  instead of creating another one; the server refuses a second note for a linked task as well.
- "Alle Aufgaben" uses each task's own list columns for the status selector, dot and detail.
- Whisper: send vad_filter (STT_VAD_FILTER, default on) and drop a verbatim repeated tail of
  sentences or words from the transcript.
- Task detail: narrower time field, wider date field in the desktop sidebar.

v0.37.2.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/config/config.go

@@ -91,6 +91,7 @@ type SpeechConfig struct {
 	MaxParallel    int // transcriptions running at the same time; more wait in line
 	PerUserPerHour int
 	TimeoutSeconds int
+	VADFilter      bool // ask the Whisper server to skip silence (fewer made-up repetitions); speaches understands it
 }
 
 // Mode is "server", "browser" or "off". The demo never uses the server, so visitors cannot keep
@@ -270,6 +271,7 @@ func Load() *Config {
 			MaxParallel:    envInt("STT_MAX_PARALLEL", 1, 1, 32),
 			PerUserPerHour: envInt("STT_PER_USER_PER_HOUR", 60, 1, 100000),
 			TimeoutSeconds: envInt("STT_TIMEOUT_SECONDS", 120, 5, 3600),
+			VADFilter:      strings.ToLower(getEnv("STT_VAD_FILTER", "true")) != "false",
 		},
 		NotifyDigestMinutes: envInt("NOTIFY_DIGEST_MINUTES", 5, 1, 1440),
 		VAPIDPublicKey:      strings.TrimSpace(os.Getenv("VAPID_PUBLIC_KEY")),