feat: add --version flag to CLI

[George-iam]

The CLI (src/cli.ts) currently supports serve, setup, status, and hook subcommands, but has no --version or -v flag. Running axme-code --version should print the version from package.json (injected at build time via the __VERSION__ esbuild define constant, available as AXME_CODE_VERSION from src/types.ts). This is a small addition to the argument parsing logic in cli.ts.

Relevant files:

• src/cli.ts — add --version / -v flag handling early in the arg parsing
• src/types.ts — AXME_CODE_VERSION constant (already exists)
• build.mjs — defines __VERSION__ at build time (no changes needed)

Acceptance criteria:

• axme-code --version prints the version string and exits
• axme-code -v does the same
• npm run build succeeds