feat: rebrand widget from games.directory to Orbit

[pacMakaveli]

Rebrand: games.directory → Orbit

The widget's own branding now reads Orbit instead of "games.directory", which was an unrealistic placeholder name.

Visible branding

• Page <title>s, the logo .name text, the logo glyph (g → o), and aria-labels across root chooser, canvas/, svg/, and legacy/.
• HQ marker name: games.directory HQ → Orbit HQ.

Source-file headers

• The /* games.directory globe — … */ banner at the top of every JS/CSS file → /* Orbit — … */.

Embed contract (⚠️ breaking)

• Inline config global: window.__GD_SCENE__ → window.__ORBIT_SCENE__.
• Persisted panel keys: gd-globe-scene / gd-globe-scene-open → orbit-scene / orbit-scene-open.
• Breaks existing embeds that set the old global, and users lose saved panel state once. Docs updated to match.

Kept intentionally

• The "extracted from the games.directory platform" origin narrative in README.md and docs/ is left as-is (per scope decision) — Orbit is the globe widget; games.directory remains the platform it came from.

Root page cleanup

• Removed the usage/disclaimer footer from the root chooser page and folded the local-server note into docs/USAGE.md (added a Running locally section).

Verification

• prettier --check passes on all changed files; all changed JS re-checked with node --check.
• No orphaned __GD_ / gd-globe identifiers remain (grep-verified); only the intentional games.directory platform reference in scene-schema.js is kept.