Add integrated Git conflict resolution workflow

Introduce a three-pane UIMergeView with an editable shared result
document, conflict navigation and acceptance actions, live diff
highlighting, synchronized scrolling, and contextual pane labels.

Read conflict stages directly from Git's index, detect paused merge
operations, restore conflict sessions, and support resolving, staging,
recreating, continuing, committing, and aborting operations.

Add repository-aware conflict state handling, safe asynchronous
lifetimes, merge operation UI, configurable key modifiers, i18n
strings, and focused merge-view and Git conflict tests.

.agent/rules/project-introduction.md

@@ -38,3 +38,20 @@ Follow eepp's established namespace style: prefer the appropriate `using namespa
 declarations and unqualified eepp type names, such as `UISplitter`, over repeatedly spelling fully
 qualified names such as `EE::UI::UISplitter`. Keep explicit qualification only where it is required
 to resolve ambiguity or avoid importing an unusually broad namespace into an unsuitable scope.
+
+## Control-Statement Braces
+
+Use braces around the body of an `if`, `else`, `for`, `while`, or similar control statement whenever
+that body occupies more than one physical source line. A statement remains visually multi-line even
+when C++ treats it as a single statement, so a wrapped function call must be braced:
+
+```cpp
+if ( condition ) {
+	object->function(
+		argument,
+		anotherArgument );
+}
+```
+
+An unbraced body is acceptable only when the complete body fits on one physical source line. Apply
+this rule when writing or modifying code; do not add unrelated braces throughout untouched code.