Add `glimpse serve` which starts geckodriver + Firefox and proxies
WebDriver requests through a Unix socket at
$XDG_RUNTIME_DIR/glimpse-<uid>.sock. All commands auto-discover the
socket and reuse the running browser session (~300ms vs ~2-3s per
command).
The proxy intercepts session create/delete to keep Firefox alive:
new session requests return the existing session ID, delete session
navigates to about:blank instead of closing Firefox.
- `glimpse serve` starts in foreground, logs to stderr
- `glimpse serve --stop` sends shutdown via socket
- `glimpse serve --status` prints JSON status
- SIGTERM/SIGINT do full cleanup (Firefox + geckodriver + socket)
- Second instance detected and rejected with exit code 1
- GLIMPSE_SOCKET_PATH env var for test isolation
- Three new smoke tests for serve lifecycle
Evan Reichard
e3d7c28820