Adds a standalone IPC example: the library serving itself over a CBOR socket.
examples/timer/ipc_chronos/serve.nim compiles into libmy_timer only under
-d:ffiIpcServe (every other build untouched) and runs a chronos socket server
that, per request, decodes CBOR at the socket edge and calls the library's own
async procs directly — native, in-process, zero serialization between the
socket and the logic, no FFI boundary, no callback bridge. Exposed as
my_timer_serve(address).
CBOR (not the native struct ABI) is correct at the wire here: a relay's data is
serialized regardless, so native would only relocate the decode and add
marshalling for no gain — native locally, CBOR for IPC.
serve_host.nim starts it; client.nim is a lib-free chronos client. Both use
chronos sockets, so the example builds and runs on Linux, macOS and Windows
over TCP (unix sockets are a POSIX bonus).
CI: tests/e2e/ipc/run_roundtrip.nim builds the dylib + host + client, spawns
the server and round-trips over loopback TCP asserting the replies; wired as
`nimble test_ipc` and a 3-OS CI matrix (ubuntu/macos/windows).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
