Add tennis (ATP/WTA) support via a Live Tennis API provider

[bensynapse]

Follows up on #230. Adds tennis (ATP/WTA) as a league, built exactly as we discussed and PR'd against development.

Disclosure: I run the Live Tennis API, so this is vendor-authored — judge accordingly. We also ship a dedicated module, MMM-LiveTennis; this provider is for people who'd rather see tennis inside one unified MMM-MyScoreboard than run a second module. No conflict from our side.

What's here

• providers/LiveTennisAPI.js — new provider implementing the same getScores(payload, gameDate, callback) contract as PWHL.js: its own POLL_FREQUENCY, self-starting poll, and normalization to the module's game object. Registered in node_helper.js.
• League codes ATP, WTA, and TENNIS (all tours) added to supportedLeagues in MMM-MyScoreboard.js.
• No schema change. The teams array is reused for player surnames (teams: ['Alcaraz', 'Djokovic']), matched case-insensitively against both players. Omit it for the full slate.
• Zero renderer changes. Sets won go into the two score slots; the status line carries the set-by-set games (6-4 3-6 2-1), current game points (40-30, or TB 5-3 in a tiebreak), and a BP marker on break point; a • marks the server.
• README — a Tennis (ATP / WTA / TENNIS) section documents setup, the surname convention, and the API caveats.

API and the honest limits (documented in the README)

• Data is the Live Tennis API free tier: GET /matches?status=live and ?status=upcoming, keyed with X-API-Key. One shared 15-minute poll spends two calls per refresh regardless of how many tennis leagues you follow (one cache feeds them all) — ~96 calls/day, inside the free 100/day (also 30/min).
• That is fine for a mirror, not for sustained fast polling (which needs a paid tier), and the free tier serves live + upcoming only — completed/final results are a paid History surface, so the tennis rows show today's in-progress and scheduled matches. This is all stated plainly next to the free-key signup, as you asked.

Config example

{
  module: 'MMM-MyScoreboard',
  position: 'top_left',
  config: {
    liveTennisApiKey: 'YOUR_FREE_KEY',
    sports: [
      { league: 'ATP', teams: ['Alcaraz', 'Djokovic'] },
      { league: 'WTA', teams: ['Gauff', 'Swiatek'] },
    ],
  },
},

Checks

• npm run lint — clean.
• npm run test:unit — 129 pass, including a new tests/unit/providers/LiveTennisAPI.test.js (18 subtests: fetch/combine, tour & surname filtering, set/tiebreak/break-point formatting, error handling).
• I didn't run the Playwright e2e suite since it needs the MagicMirror bootstrap + a live key; happy to if you'd like.

Nothing touches the other sports' code paths. Happy to adjust naming, the serving/BP presentation, or anything else to fit your conventions. I can send you a free key to test against a live slate — just say where.