Add Live Tennis MCP server

[bensynapse]

Adds the Live Tennis MCP Server as a context-server extension.

Repository: https://github.com/livetennisapi/zed-livetennis-mcp

Real-time tennis for the Zed agent panel — live scores, upcoming matches, results, player profiles and fixtures across ATP, WTA, Challenger and ITF, via the Live Tennis API's MCP server (12 read-only tools). Odds and win-probability tools exist but require a paid plan; the free tier (no card) covers scores/players/fixtures: https://livetennisapi.com/subscribe/free

Implementation notes, per the contributing guidelines:

• The MCP server is not vendored — the extension installs the livetennisapi-mcp npm package at runtime via npm_install_package (pinned to latest) and spawns it with node_binary_path().
• The API key is taken only from ContextServerSettings and passed as an env var to the spawned server; the extension never reads the ambient environment. context_server_configuration is implemented, so an unconfigured user gets setup instructions with a copy-pasteable settings block rather than a bare error.
• MIT licensed, Cargo.lock committed, builds clean against zed_extension_api 0.7 on wasm32-wasip2 from a fresh clone with --locked.
• Tested locally as a dev extension on Zed 1.11.3: the extension loads, the unconfigured path renders the setup instructions, and with a key configured Zed's own MCP client received all 12 tool schemas over its live connection (verified in Zed.log, tools/list in ~10ms); tool calls against the installed artifact returned live match data.
• Submodule uses the HTTPS URL; entry placed by sort-extensions; forked from a personal account.

[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: Ben.
This is most likely caused by a git client misconfiguration; please make sure to:

1. check if your git client is configured with an email to sign commits git config --list | grep email
2. If not, set it up using git config --global user.email email@example.com
3. Make sure that the git commit email is configured in your GitHub account settings, see https://github.com/settings/emails

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @bensynapse on file. You can sign our CLA at https://zed.dev/cla. Once you've signed, post a comment here that says '@cla-bot check'.

[bensynapse]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!