add git subsystem — daemon-side status, diff, operations + IPC

Shell-outs to git for status (porcelain v1/v2), unified-diff
parsing, and operations (stage, unstage, hunk-apply, discard,
commit, stash, log, pull, push). IPC verbs git.* registered on
the daemon dispatcher with git.changed event emission on
mutations. 42 new core tests.

Co-Authored-By: Claude <noreply@anthropic.com>

test/git/diff_test.dart

@@ -0,0 +1,213 @@
+import 'dart:io';
+
+import 'package:clide/src/git/diff.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('parseDiffOutput', () {
+    test('parses a simple modification', () {
+      const output = '''diff --git a/file.txt b/file.txt
+index abc1234..def5678 100644
+--- a/file.txt
++++ b/file.txt
+@@ -1,3 +1,4 @@
+ line1
+-line2
++line2-modified
++line3-new
+ line4
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.path, 'file.txt');
+      expect(diffs.first.hunks, hasLength(1));
+      expect(diffs.first.additions, 2);
+      expect(diffs.first.removals, 1);
+    });
+
+    test('parses a new file', () {
+      const output = '''diff --git a/new.txt b/new.txt
+new file mode 100644
+index 0000000..abc1234
+--- /dev/null
++++ b/new.txt
+@@ -0,0 +1,2 @@
++hello
++world
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.isNew, isTrue);
+      expect(diffs.first.additions, 2);
+    });
+
+    test('parses a deleted file', () {
+      const output = '''diff --git a/old.txt b/old.txt
+deleted file mode 100644
+index abc1234..0000000
+--- a/old.txt
++++ /dev/null
+@@ -1,2 +0,0 @@
+-hello
+-world
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.isDeleted, isTrue);
+      expect(diffs.first.removals, 2);
+    });
+
+    test('parses a rename', () {
+      const output = '''diff --git a/old.txt b/new.txt
+similarity index 100%
+rename from old.txt
+rename to new.txt
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.isRenamed, isTrue);
+      expect(diffs.first.path, 'new.txt');
+      expect(diffs.first.oldPath, 'old.txt');
+    });
+
+    test('parses multiple hunks', () {
+      const output = '''diff --git a/multi.txt b/multi.txt
+index abc..def 100644
+--- a/multi.txt
++++ b/multi.txt
+@@ -1,3 +1,3 @@
+ line1
+-old2
++new2
+ line3
+@@ -10,3 +10,3 @@
+ line10
+-old11
++new11
+ line12
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.hunks, hasLength(2));
+      expect(diffs.first.hunks[0].oldStart, 1);
+      expect(diffs.first.hunks[1].oldStart, 10);
+    });
+
+    test('parses binary file', () {
+      const output = '''diff --git a/image.png b/image.png
+Binary files a/image.png and b/image.png differ
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.isBinary, isTrue);
+      expect(diffs.first.hunks, isEmpty);
+    });
+
+    test('empty output returns empty list', () {
+      expect(parseDiffOutput(''), isEmpty);
+    });
+
+    test('hunk line numbers are correct', () {
+      const output = '''diff --git a/f.txt b/f.txt
+index abc..def 100644
+--- a/f.txt
++++ b/f.txt
+@@ -5,4 +5,5 @@
+ ctx
+-removed
++added1
++added2
+ ctx2
+''';
+      final diffs = parseDiffOutput(output);
+      final hunk = diffs.first.hunks.first;
+      expect(hunk.oldStart, 5);
+      expect(hunk.newStart, 5);
+
+      final additions = hunk.lines.where((l) => l.kind == DiffLineKind.addition).toList();
+      expect(additions[0].newLineNo, 6);
+      expect(additions[1].newLineNo, 7);
+
+      final removals = hunk.lines.where((l) => l.kind == DiffLineKind.removal).toList();
+      expect(removals[0].oldLineNo, 6);
+    });
+
+    test('multiple diffs in one output', () {
+      const output = '''diff --git a/a.txt b/a.txt
+index abc..def 100644
+--- a/a.txt
++++ b/a.txt
+@@ -1 +1 @@
+-old
++new
+diff --git a/b.txt b/b.txt
+index abc..def 100644
+--- a/b.txt
++++ b/b.txt
+@@ -1 +1 @@
+-old
++new
+''';
+      final diffs = parseDiffOutput(output);
+      expect(diffs, hasLength(2));
+      expect(diffs[0].path, 'a.txt');
+      expect(diffs[1].path, 'b.txt');
+    });
+  });
+
+  group('gitDiff (live)', () {
+    late Directory sandbox;
+
+    setUp(() async {
+      sandbox = await Directory.systemTemp.createTemp('clide-git-diff-test-');
+      await Process.run('git', ['init'], workingDirectory: sandbox.path);
+      await Process.run(
+        'git',
+        ['config', 'user.email', 'test@test.com'],
+        workingDirectory: sandbox.path,
+      );
+      await Process.run(
+        'git',
+        ['config', 'user.name', 'Test'],
+        workingDirectory: sandbox.path,
+      );
+      await File('${sandbox.path}/file.txt').writeAsString('line1\nline2\n');
+      await Process.run('git', ['add', '.'], workingDirectory: sandbox.path);
+      await Process.run(
+        'git',
+        ['commit', '-m', 'init'],
+        workingDirectory: sandbox.path,
+      );
+    });
+
+    tearDown(() async {
+      if (sandbox.existsSync()) sandbox.deleteSync(recursive: true);
+    });
+
+    test('returns unstaged diff after modification', () async {
+      await File('${sandbox.path}/file.txt')
+          .writeAsString('line1\nmodified\n');
+      final diffs = await gitDiff(sandbox);
+      expect(diffs, hasLength(1));
+      expect(diffs.first.path, 'file.txt');
+      expect(diffs.first.additions, greaterThan(0));
+    });
+
+    test('returns staged diff with staged: true', () async {
+      await File('${sandbox.path}/file.txt')
+          .writeAsString('line1\nmodified\n');
+      await Process.run(
+        'git',
+        ['add', 'file.txt'],
+        workingDirectory: sandbox.path,
+      );
+      final diffs = await gitDiff(sandbox, staged: true);
+      expect(diffs, hasLength(1));
+    });
+
+    test('returns empty for clean repo', () async {
+      final diffs = await gitDiff(sandbox);
+      expect(diffs, isEmpty);
+    });
+  });
+}