feat(programmer): day rows builder + work-log workDate

- Add workDate field to ProgrammerTaskWorkLog (defaults to Manila day of createdAt)
- Add deltaJsonToPlainText function to quill_field.dart for Delta/plain text conversion
- Implement buildDayRows function to generate day sheet rows with proper sorting
- Implement DaySheetRow serialization and deserialization
- Add comprehensive tests for day rows builder and workDate field
- Verify backward compatibility via existing programmer_task_ledger_test
Co-Authored-By: claude-flow <ruv@ruv.net>

lib/widgets/quill_field.dart

@@ -3,6 +3,26 @@ import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:flutter_quill/flutter_quill.dart' as quill;
 
+/// Convert a stored Delta JSON or plain text string to trimmed plain text.
+/// - Delta JSON (starts with '[') is decoded and converted to plain text
+/// - Non-JSON strings are returned trimmed as-is
+/// - null returns empty string
+String deltaJsonToPlainText(String? stored) {
+  if (stored == null) return '';
+  final trimmed = stored.trim();
+  if (trimmed.isEmpty) return '';
+  if (trimmed.startsWith('[')) {
+    try {
+      final decoded = jsonDecode(trimmed);
+      if (decoded is List) {
+        final doc = quill.Document.fromJson(decoded);
+        return doc.toPlainText().trim();
+      }
+    } catch (_) {}
+  }
+  return trimmed;
+}
+
 /// Parses a stored Delta-JSON string into a [quill.QuillController], or returns
 /// an empty one. Callers own the controller and must dispose it.
 quill.QuillController quillControllerFromDelta(String? deltaJson) {