fix: use ~/.agent-browser for socket files instead of TMPDIR (#180)

* fix: use ~/.agent-browser for socket files instead of TMPDIR

This fixes issue #163 where different TMPDIR values (common with
tmux/screen/VSCode/IntelliJ) caused the CLI and daemon to use
different socket paths.

Socket directory priority:
1. AGENT_BROWSER_SOCKET_DIR (explicit override)
2. $XDG_RUNTIME_DIR/agent-browser (Linux standard)
3. ~/.agent-browser (fallback, like Docker Desktop)

Both CLI (Rust) and daemon (Node.js) now use the same logic.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix: session list now looks in correct socket directory

- Make get_socket_dir() public in connection.rs
- Update session list to use get_socket_dir() instead of temp_dir()
- Update pid file pattern from agent-browser-{session}.pid to {session}.pid
- Add tmpdir fallback to daemon.ts when homedir is unavailable

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* test: add unit tests for socket directory resolution

Add comprehensive tests for get_socket_dir/getSocketDir to verify:
- AGENT_BROWSER_SOCKET_DIR takes priority
- Empty strings are ignored (fixes Rust/TypeScript consistency)
- XDG_RUNTIME_DIR fallback works correctly
- Home directory fallback when env vars unset

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

cli/Cargo.toml

@@ -8,6 +8,7 @@ license = "Apache-2.0"
 [dependencies]
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+dirs = "5.0"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"