Add globe leader map with MaxMind geolocation

[notwedtm]

Summary

• add a MaxMind-backed GeoIP loader with configurable download paths and caching for IP lookups
• introduce the /api/leader-path endpoint plus a new /map Globe.GL page that renders upcoming leader routes and links from the main view/docs
• update docs/README and add unit and integration coverage for the new endpoints

Screenshots

• Unable to capture in this environment (crates.io/network access blocked, so the dev server cannot be started for a screenshot).

Testing

• cargo test (fails: crates.io index blocked with 403 CONNECT tunnel errors)

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Codex Task