feat(todo): comments and descriptions in the editor (ADR 0033, D38)

Comments and the descriptions of tasks, projects, sections and filters
become the editor's document on halkyon_editor; names and titles stay
text. Rows written as text read as notes and become documents when next
saved, the server seeing only sealed bytes, so there is no migration.

Sections' descriptions can now be written, and a project's shows above
its tasks. Android answers whether a link can open only for what is
declared, so Todo declares http and https.

Whats-New: Comments and descriptions take rich text: headings, lists, checklists, links and more.
Whats-New-De: Kommentare und Beschreibungen können jetzt formatiert werden: Überschriften, Listen, Checklisten, Links und mehr.

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

apps/todo/halkyon_todo_flutter/android/app/src/main/AndroidManifest.xml

@@ -121,6 +121,17 @@
             <action android:name="android.intent.action.PROCESS_TEXT"/>
             <data android:mimeType="text/plain"/>
         </intent>
+        <!-- Links in a note: the editor asks whether one can open before it
+             opens it, which Android answers only for what is declared
+             (ADR 0033, D38). -->
+        <intent>
+            <action android:name="android.intent.action.VIEW"/>
+            <data android:scheme="https"/>
+        </intent>
+        <intent>
+            <action android:name="android.intent.action.VIEW"/>
+            <data android:scheme="http"/>
+        </intent>
         <!-- The device's speech recogniser, for dictation (ADR 0033, D29). -->
         <intent>
             <action android:name="android.speech.RecognitionService"/>