Add optional stateless MCP server for the real browser

Expose a conservative browser-cli tool surface to MCP hosts without
duplicating browser-control logic: every tool is a thin adapter over the
existing Python SDK, and each call builds a fresh BrowserCLI so the real
browser stays the only owner of tab and navigation state.

The MCP process resolves BROWSER_CLI_PROFILE, BROWSER_CLI_REMOTE, and
BROWSER_CLI_KEY explicitly instead of passing None down, so a pinned server
targets one browser rather than fanning listing calls out across every
connected browser. Explicit tool arguments still win.

Tool names keep a browser_ prefix for hosts that expose raw MCP names, while
BROWSER_CLI_MCP_TOOL_PREFIX lets hosts that already namespace by server drop
it and avoid names like browser_cli_testing_browser_tabs_list.

JavaScript evaluation, raw commands, storage writes, and session import stay
unexposed, and Streamable HTTP refuses non-loopback binds because the endpoint
has no authentication of its own; remote browsers go through browser-cli's
authenticated remote transport instead.

MCP stays an optional extra, so normal installs are unaffected.

pyproject.toml

@@ -22,9 +22,13 @@ Issues = "https://git.yiprawr.dev/Automatisation/browser-cli/issues"
 [project.optional-dependencies]
 # Better/faster remote response compression than the stdlib zlib/gzip fallback.
 fast = ["zstandard>=0.22"]
+mcp = [
+    "mcp>=2,<3",
+]
 
 [project.scripts]
 browser-cli = "browser_cli.cli:main"
+browser-cli-mcp = "browser_cli.mcp.server:main"
 
 [dependency-groups]
 dev = [