CLI version and unknown flags exit silently #309

The published @notionhq/notion-mcp-server@2.2.1 binary supports --help, but --version and unknown top-level flags both exit successfully without printing anything. This makes local MCP setup harder to inspect and makes typos look like successful no-op commands.

Reproduction on Windows/PowerShell:

$work = Join-Path $env:TEMP "notion-mcp-cli-flag-repro"
Remove-Item -LiteralPath $work -Recurse -Force -ErrorAction SilentlyContinue
New-Item -ItemType Directory -Path $work | Out-Null
Set-Location $work
npm init -y | Out-Null
npm install --ignore-scripts --no-audit --no-fund @notionhq/notion-mcp-server@2.2.1
$cmd = Join-Path $work "node_modules\.bin\notion-mcp-server.cmd"
$out = & $cmd --help 2>&1; "help_exit=$LASTEXITCODE help_len=$(($out -join "`n").Length)"
$out = & $cmd --version 2>&1; "version_exit=$LASTEXITCODE version_len=$(($out -join "`n").Length)"
$out = & $cmd --definitely-not-a-real-flag 2>&1; "invalid_exit=$LASTEXITCODE invalid_len=$(($out -join "`n").Length)"

Observed:

help_exit=0 help_len=1445
version_exit=0 version_len=0
invalid_exit=0 invalid_len=0

Expected behavior:

• notion-mcp-server --version / -v should exit 0 and print the installed package version, 2.2.1 for this package.
• Unknown top-level flags should print a concise unknown-option error and exit non-zero.
• Existing --help behavior should remain unchanged.

Likely source area:

• package.json exposes bin: { "notion-mcp-server": "bin/cli.mjs" } and version 2.2.1.
• bin/cli.mjs already implements --help, so the fix should be near the same argument preflight/parser path.