Add swap file journaling for crash recovery.

- Introduced `SwapManager` for buffering and writing incremental edits to sidecar `.kte.swp` files.
- Implemented basic operations: insertion, deletion, split, join, and checkpointing.
- Added recovery design doc (`docs/plans/swap-files.md`).
- Updated editor initialization to integrate `SwapManager` instance for crash recovery across buffers.

GUIInputHandler.h

@@ -16,6 +16,13 @@ public:
 
 	~GUIInputHandler() override = default;
 
+
+	void Attach(Editor *ed) override
+	{
+		ed_ = ed;
+	}
+
+
 	// Translate an SDL event to editor command and enqueue if applicable.
 	// Returns true if it produced a mapped command or consumed input.
 	bool ProcessSDLEvent(const SDL_Event &e);
@@ -25,18 +32,13 @@ public:
 private:
 	std::mutex mu_;
 	std::queue<MappedInput> q_;
-	bool k_prefix_ = false;
+	bool k_prefix_       = false;
+	bool k_ctrl_pending_ = false; // if true, next k-suffix is treated as Ctrl- (qualifier via literal 'C' or '^')
 	// Treat ESC as a Meta prefix: next key is looked up via ESC keymap
 	bool esc_meta_ = false;
 	// When a printable keydown generated a non-text command, suppress the very next SDL_TEXTINPUT
 	// event produced by SDL for the same keystroke to avoid inserting stray characters.
 	bool suppress_text_input_once_ = false;
 
-	// Universal argument (C-u) state for GUI
-	bool uarg_active_     = false; // an argument is pending for the next command
-	bool uarg_collecting_ = false; // collecting digits / '-' right now
-	bool uarg_negative_   = false; // whether a leading '-' was supplied
-	bool uarg_had_digits_ = false; // whether any digits were supplied
-	int uarg_value_       = 0; // current absolute value (>=0)
-	std::string uarg_text_; // raw digits/minus typed for status display
+	Editor *ed_ = nullptr; // attached editor for editor-owned uarg handling
 };