CLI: --version reports the npm package version (#731)

* CLI: --version reports the npm package version

npx impeccable --version printed 3.6.0 after the 4.0.0 release because
the shim handed every argument to the engine, whose baked-in
CLI_VERSION still said 3.6.0. The shim now answers --version and -v
from its own package.json, as docs/CLI-CONTRACT.md specifies, without
locating or downloading a binary; a test covers both flags. The
engine's CLI_VERSION moves to 4.0.0 for the next engine release, with
the cli-version golden re-recorded and the delta noted.

Co-Authored-By: Claude Code <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vau2X53xGTjjTCXWMVBoNY

* CLI shim: --version wins whenever it leads, trailing arguments or not

Co-Authored-By: Claude Code <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vau2X53xGTjjTCXWMVBoNY

---------

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

tests/oracle/golden/cli-version.json

@@ -1,5 +1,5 @@
 {
-  "stdout": "3.6.0\n",
+  "stdout": "4.0.0\n",
   "stderr": "",
   "exit": 0,
   "signal": null,