refactor: implemented $PWD > cwd to prevent macOS symlink resolution

- Replaced all direct `process.cwd()` calls with `getProjectDir()` utility function across 40+ files to centralize project directory resolution logic.
- Added `getProjectDir()` and `setProjectDir()` functions to `@oh-my-pi/pi-utils/dirs` module to provide abstracted project directory management.
- Made `SessionManager.list()` method asynchronous to support asynchronous session discovery operations.
- Updated default working directory resolution throughout codebase to use `getProjectDir()` instead of `process.cwd()` for improved project directory detection.

packages/tui/README.md

@@ -443,6 +443,7 @@ Supports both slash commands and file paths.
 
 ```typescript
 import { CombinedAutocompleteProvider } from "@oh-my-pi/pi-tui";
+import { getProjectDir } from "@oh-my-pi/pi-utils/dirs";
 
 const provider = new CombinedAutocompleteProvider(
 	[
@@ -450,7 +451,7 @@ const provider = new CombinedAutocompleteProvider(
 		{ name: "clear", description: "Clear screen" },
 		{ name: "delete", description: "Delete last message" },
 	],
-	process.cwd() // base path for file completion
+	getProjectDir() // base path for file completion
 );
 
 editor.setAutocompleteProvider(provider);