feat(log): widen the dump budget to fit a debug session

lib/core/diagnostics/debug_dump.dart

@@ -7,7 +7,7 @@ library;
 /// a chat window will show without collapsing. The diagnostics are the part
 /// that cannot be trimmed (every row answers a question somebody asks), so the
 /// log takes whatever is left.
-const int dumpLimit = 4000;
+const int dumpLimit = 39995;
 
 const String _diagnosticsHeading = '=== 除錯資訊 ===';
 const String _logHeading = '=== 日誌紀錄 ===';

lib/core/diagnostics/haste_api.dart

@@ -7,8 +7,9 @@ import 'package:dpip/core/diagnostics/dump_uploader.dart';
 /// Posts a dump and returns the URL to read it at.
 ///
 /// A paste rather than an attachment because of where these end up: a bug
-/// report in Discord or an issue, where 4000 characters of log pasted inline
-/// buries everything around it and an attached file is not read at all.
+/// report in Discord or an issue, where tens of thousands of characters of log
+/// pasted inline buries everything around it and an attached file is not read
+/// at all.
 class HasteApi implements DumpUploader {
   const HasteApi(this._client);
 

lib/shared/diagnostics/dump_action.dart

@@ -22,8 +22,9 @@ import 'package:talker_flutter/talker_flutter.dart';
 ///
 /// The two halves answer different questions and a report needs both: the
 /// diagnostics say what this build and this device are, the log says what they
-/// just did. Pasting 4000 characters into a chat buries the conversation they
-/// are part of, so they go to a paste and only the link comes back.
+/// just did. Pasting tens of thousands of characters into a chat buries the
+/// conversation they are part of, so they go to a paste and only the link
+/// comes back.
 ///
 /// Returns true when a link was produced. Failures are reported to the user
 /// here and logged; the caller only has to stop showing its spinner.

test/core/diagnostics/debug_dump_test.dart

@@ -54,10 +54,11 @@ void main() {
   test('diagnostics are never cut to make room', () {
     // A partial diagnostic reads as a complete one and is answered as if it
     // were, which is worse than carrying no log at all.
-    final big = 'Version: 26w34b\n${'x' * 5000}';
+    // Sized past the limit so the log must be dropped for the diagnostics to fit.
+    final big = 'Version: 26w34b\n${'x' * (dumpLimit + 1000)}';
     final out = buildDump(diagnostics: big, logLines: lines(50));
     expect(out, contains('Version: 26w34b'));
-    expect(out, contains('x' * 5000));
+    expect(out, contains('x' * (dumpLimit + 1000)));
     expect(out, isNot(contains('line 0')));
   });
 

test/core/logging/log_benign_assert_test.dart

@@ -2,7 +2,7 @@
 /// into the log that sheet belongs to — a debug assert from talker_flutter,
 /// which paints that sheet as a coloured box with bare `ListTile`s inside it.
 /// Nothing this app can fix, and nothing a user is affected by, but it filled
-/// the terminal, the log page and the 4000-character dump budget.
+/// the terminal, the log page and the dump budget.
 ///
 /// The tests here pin the two halves of the compromise: it is said once, so it
 /// is on the record, and it is said only once, so it cannot flood. A real error