Refactor SessionManager to use static factory methods

- Add factory methods: create(cwd), open(path), continueRecent(cwd), inMemory()
- Add static list(cwd) for session listing
- Make constructor private, pass cwd explicitly
- Update SDK to take sessionManager instead of sessionFile options
- Update main.ts to create SessionManager based on CLI flags
- Update SessionSelectorComponent to take sessions[] instead of SessionManager
- Update tests to use factory methods

packages/coding-agent/src/cli/session-picker.ts

@@ -3,17 +3,17 @@
  */
 
 import { ProcessTerminal, TUI } from "@mariozechner/pi-tui";
-import type { SessionManager } from "../core/session-manager.js";
+import type { SessionInfo } from "../core/session-manager.js";
 import { SessionSelectorComponent } from "../modes/interactive/components/session-selector.js";
 
 /** Show TUI session selector and return selected session path or null if cancelled */
-export async function selectSession(sessionManager: SessionManager): Promise<string | null> {
+export async function selectSession(sessions: SessionInfo[]): Promise<string | null> {
 	return new Promise((resolve) => {
 		const ui = new TUI(new ProcessTerminal());
 		let resolved = false;
 
 		const selector = new SessionSelectorComponent(
-			sessionManager,
+			sessions,
 			(path: string) => {
 				if (!resolved) {
 					resolved = true;