Fix nREPL on Windows; add a version string

The nREPL server bound its loopback socket through libc process symbols,
which don't carry the socket entry points on Windows — they live in
ws2_32.dll and aren't in joltc.exe's export table, so --nrepl-server died
with "no entry for socket". Load ws2_32 before the foreign bindings there,
call WSAStartup once, and use Winsock's closesocket and int-typed
recv/send. Also fix SOL_SOCKET/SO_REUSEADDR, which the old macos-only
check got wrong on Windows.

Bake a version string into the self-contained binary at build time (from
$JOLT_VERSION, else git describe) and expose it via jolt.host/jolt-version:
--version / -V print it, and it shows in --help, the repl banner, and the
nREPL startup line. Dev runs off bin/joltc read it from git describe.

Add -e to the help output.

.github/workflows/release.yml

@@ -154,6 +154,10 @@ jobs:
       # dev-machine check — see jolt-8479). `make joltc-release`, not `make joltc`.
       - name: Build joltc (release)
         run: make joltc-release
+        env:
+          # Bake the release tag into the binary (build-joltc falls back to
+          # `git describe` when this is empty, e.g. a workflow_dispatch dry run).
+          JOLT_VERSION: ${{ startsWith(github.ref, 'refs/tags/') && github.ref_name || '' }}
 
       - name: Inspect the binary (Windows)
         if: runner.os == 'Windows'