Refactor code for consistency and enhanced functionality.

- Normalize path handling for buffer operations, supporting tilde expansion and absolute paths.
- Introduce `DisplayNameFor` to uniquely resolve buffer display names, minimizing filename clashes.
- Add new commands: `ShowWorkingDirectory` and `ChangeWorkingDirectory`.
- Refine keybindings and enhance existing commands for improved command flow.
- Adjust GUI and terminal renderers to display total line counts alongside filenames.
- Update coding style to align with project guidelines.

Editor.h

@@ -302,7 +302,7 @@ public:
 
 
 	// --- Generic Prompt subsystem (for search, open-file, save-as, etc.) ---
-	enum class PromptKind { None = 0, Search, OpenFile, SaveAs, Confirm, BufferSwitch, GotoLine };
+	enum class PromptKind { None = 0, Search, OpenFile, SaveAs, Confirm, BufferSwitch, GotoLine, Chdir };
 
 
 	void StartPrompt(PromptKind kind, const std::string &label, const std::string &initial)
@@ -409,6 +409,11 @@ public:
 
 	const Buffer *CurrentBuffer() const;
 
+	// Compute a display-friendly short name for a buffer path that is the
+	// shortest unique suffix among all open buffers. If buffer has no name,
+	// returns "[no name]".
+	[[nodiscard]] std::string DisplayNameFor(const Buffer &buf) const;
+
 	// Add an existing buffer (copy/move) or open from file path
 	std::size_t AddBuffer(const Buffer &buf);