feat(learn): voice mode goes, as a spoken conversation isn't wanted (ADR 0021, D68 withdrawn)

The developer's review of 4 Nov 2026: "an actual conversation with the AI
chatbot is not desirable and necessary". The field's voice-mode button,
the screen it opened, reading answers aloud and its texts go, and with
them flutter_tts, its patched copy in third_party/ (one override fewer),
the TTS_SERVICE query in the manifest and the plugin's registrants. The
microphone stays and dictates into the question. ImageApproval is the
conversation sheet's own again, as only voice mode needed it.

Whats-New: Voice mode is gone; the microphone dictates into your question.
Whats-New-De: Der Sprachmodus ist weg; das Mikrofon diktiert in deine Frage.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

docs/adr/0021-private-instance-and-assistant.md

@@ -462,8 +462,9 @@ assistants' effort work:
     asking for the microphone only once it is tapped; on Linux there is none, and the
     field shows no microphone. On Android the recogniser may send the sound to Google or
     the phone's maker, which the instance's privacy page says; the instance never gets it.
-- **D68 Voice mode is a conversation spoken, as Claude's "Let's talk"** (the developer's
-  review of 3 Nov 2026, full conversation chosen over dictation alone): beside the
+- **D68 Voice mode is a conversation spoken, as Claude's "Let's talk"** (withdrawn on
+  4 Nov 2026, below; the developer's review of 3 Nov 2026, full conversation chosen
+  over dictation alone): beside the
   microphone, while nothing could be sent, a button opens it over the whole screen (no
   bar beneath), with a glow rising from the foot of it, brighter while it listens or
   reads, a big microphone and one row: + attaching to the next question, who answers (any
@@ -487,6 +488,12 @@ assistants' effort work:
     mode (as no microphone, D67); where nothing reads aloud (`flutter_tts` has no Linux,
     and a phone may lack the language), answers are shown in it as text, and it listens
     again at once, as with the speaker off. The speaker starts on.
+  - **Withdrawn on 4 Nov 2026** (the developer's review: "an actual conversation with
+    the AI chatbot is not desirable and necessary"): voice mode is gone, with
+    `flutter_tts`, its patched copy in `third_party/` and the `TTS_SERVICE` query. The
+    microphone stays, dictating into the question (D69), so speaking still writes a
+    question the person reads before sending. Nothing kept changes: conversations begun
+    in voice mode were kept as any other (D48) and read as before.
 
 As built on 26 Oct, for v0.22.0 (build 25, which the server needs: `minimumAppBuild` 25,
 as older apps read limits per grant), D57–D63 read so where they left something open: