feat: replace mail protocol with smolmail and rebuild the UI

lib/presentation/screens/compose_screen.dart

@@ -0,0 +1,127 @@
+import "package:auto_route/auto_route.dart";
+import "package:flutter/material.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+
+import "package:smol_mail/data/providers/providers.dart";
+import "package:smol_mail/presentation/widgets/primary_button.dart";
+import "package:smol_mail/presentation/widgets/small_loading_spinner.dart";
+import "package:smol_mail/presentation/theme/app_colors.dart";
+import "package:smol_mail/shared/utils/snackbar.dart";
+import "package:smol_mail/smol/errors.dart";
+
+/// One tap seals one envelope; the button disables while the send is in
+/// flight so a second tap cannot seal a second message.
+@RoutePage()
+class ComposeScreen extends ConsumerStatefulWidget {
+  final String? to;
+  final String? subject;
+
+  const ComposeScreen({
+    super.key,
+    this.to,
+    this.subject,
+  });
+
+  @override
+  ConsumerState<ComposeScreen> createState() => _ComposeScreenState();
+}
+
+class _ComposeScreenState extends ConsumerState<ComposeScreen> {
+  late final toController = TextEditingController(text: widget.to ?? "");
+  late final subjectController =
+      TextEditingController(text: widget.subject ?? "");
+  final bodyController = TextEditingController();
+  bool anonymous = false;
+  bool busy = false;
+
+  @override
+  void dispose() {
+    toController.dispose();
+    subjectController.dispose();
+    bodyController.dispose();
+    super.dispose();
+  }
+
+  Future<void> _send() async {
+    final client = ref.read(clientProvider);
+    setState(() => busy = true);
+    try {
+      final to = await client.send(
+        toController.text,
+        subjectController.text,
+        bodyController.text,
+        anonymous: anonymous,
+      );
+      ref.read(revisionProvider.notifier).bump();
+      if (mounted) {
+        ScaffoldMessenger.of(context)
+            .showSnackBar(SnackBar(content: Text("sent to $to")));
+        AutoRouter.of(context).pop();
+      }
+    } on SmolError catch (err) {
+      if (mounted) {
+        showErrorSnackBar(context, err.message);
+      }
+    } finally {
+      if (mounted) setState(() => busy = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text("Write")),
+      body: SingleChildScrollView(
+        padding: const EdgeInsets.all(20),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            TextField(
+              controller: toController,
+              decoration: InputDecoration(
+                labelText: "To",
+                hintText: "user@host[:1961] or smol://user@host/key",
+                filled: true,
+                fillColor: Theme.of(context).extension<AppColors>()!.cardFill,
+              ),
+            ),
+            const SizedBox(height: 15),
+            TextField(
+              controller: subjectController,
+              decoration: InputDecoration(
+                labelText: "Subject",
+                filled: true,
+                fillColor: Theme.of(context).extension<AppColors>()!.cardFill,
+              ),
+            ),
+            const SizedBox(height: 15),
+            TextField(
+              controller: bodyController,
+              maxLines: 12,
+              decoration: InputDecoration(
+                labelText: "Body",
+                filled: true,
+                fillColor: Theme.of(context).extension<AppColors>()!.cardFill,
+              ),
+            ),
+            SwitchListTile(
+              value: anonymous,
+              onChanged: (value) => setState(() => anonymous = value),
+              title: Text(
+                "Anonymous (omit the signed Reply-To)",
+                style: Theme.of(context).textTheme.bodySmall,
+              ),
+            ),
+            const SizedBox(height: 10),
+            Center(
+              child: PrimaryButton(
+                onPressed: busy ? () {} : _send,
+                child: busy ? const SmallLoadingSpinner() : const Text("Send"),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}