feat: support smol:// QR sharing, deep links and in-dialog scanning

lib/presentation/screens/import_contact_dialog.dart

@@ -0,0 +1,131 @@
+import "package:auto_route/auto_route.dart";
+import "package:flutter/material.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:mobile_scanner/mobile_scanner.dart";
+
+import "package:smol_mail/data/providers/providers.dart";
+import "package:smol_mail/presentation/app_widget.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";
+import "package:smol_mail/smol/link.dart";
+
+/// The §8 strong path: a self-certifying smol:// address is pasted, scanned
+/// or deep-linked in, and the user confirms before its key is bound. A
+/// routed dialog page rather than showDialog, so auto_route's platform-link
+/// handling — which pops pageless top routes — leaves it standing. The QR
+/// icon swaps the text field for a camera view; a scanned URI only fills
+/// the field, the Import tap is still what binds the key.
+@RoutePage()
+class ImportContactDialogScreen extends ConsumerStatefulWidget {
+  final String? prefill;
+
+  const ImportContactDialogScreen({super.key, this.prefill});
+
+  @override
+  ConsumerState<ImportContactDialogScreen> createState() =>
+      ImportContactDialogScreenState();
+}
+
+class ImportContactDialogScreenState
+    extends ConsumerState<ImportContactDialogScreen> {
+  late final controller = TextEditingController(text: widget.prefill ?? "");
+  bool scanning = false;
+  MobileScannerController? _scanner;
+
+  @override
+  void dispose() {
+    _scanner?.dispose();
+    controller.dispose();
+    super.dispose();
+  }
+
+  void _toggleScan() {
+    setState(() {
+      _scanner?.dispose();
+      _scanner =
+          scanning ? null : MobileScannerController(formats: [BarcodeFormat.qrCode]);
+      scanning = !scanning;
+    });
+  }
+
+  // Only a URI fumi accepts fills the field; anything else the camera sees
+  // is not for this dialog, so scanning simply continues.
+  void _onDetect(BarcodeCapture capture) {
+    if (!scanning) return;
+    for (final barcode in capture.barcodes) {
+      final raw = barcode.rawValue?.trim();
+      if (raw != null && parseSmolLink(raw) != null) {
+        controller.text = raw;
+        _toggleScan();
+        return;
+      }
+    }
+  }
+
+  void _import() {
+    final text = controller.text;
+    if (text.trim().isEmpty) return;
+    try {
+      ref.read(clientProvider).importContact(text);
+      ref.read(revisionProvider.notifier).bump();
+      rootScaffoldMessengerKey.currentState?.showSnackBar(
+        const SnackBar(content: Text("contact imported (verified key)")),
+      );
+      AutoRouter.of(context).pop();
+    } on SmolError catch (err) {
+      showErrorSnackBar(context, err.message);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AlertDialog(
+      backgroundColor: Theme.of(context).extension<AppColors>()!.cardFill,
+      title: const Text("Import contact"),
+      content: scanning
+          ? SizedBox(
+              height: 220,
+              width: double.maxFinite,
+              child: ClipRRect(
+                borderRadius: BorderRadius.circular(12),
+                child: MobileScanner(
+                  controller: _scanner!,
+                  onDetect: _onDetect,
+                  errorBuilder: (context, error) => Center(
+                    child: Padding(
+                      padding: const EdgeInsets.all(12),
+                      child: Text(
+                        error.errorCode.name,
+                        style: Theme.of(context).textTheme.labelSmall,
+                        textAlign: TextAlign.center,
+                      ),
+                    ),
+                  ),
+                ),
+              ),
+            )
+          : TextField(
+              controller: controller,
+              autofocus: true,
+              onSubmitted: (_) => _import(),
+              decoration: InputDecoration(
+                hintText: "smol://user@host/key",
+                filled: true,
+                fillColor: Theme.of(context).colorScheme.surface,
+              ),
+            ),
+      actions: [
+        IconButton(
+          tooltip: scanning ? "Type the address" : "Scan a QR code",
+          onPressed: _toggleScan,
+          icon: Icon(scanning ? Icons.keyboard : Icons.qr_code_scanner),
+        ),
+        TextButton(
+          onPressed: _import,
+          child: const Text("Import"),
+        ),
+      ],
+    );
+  }
+}