fix(cyber): make GeoIP centroid fallback jitter deterministic

[fuleinist]

Uses a hash of the country code to generate deterministic jitter, so the same threat from the same country always appears at the same coordinates instead of jumping around on each request.

Fixes issue #203

[vercel]

Someone is attempting to deploy a commit to the Elie Team on Vercel.

A member of the Team first needs to authorize it.

[koala73]

Thanks for the PR! Clean, focused change — the intent is solid and the fix addresses the re-render jitter problem nicely.

A few notes:

🔴 Blocking: Anagram country codes collide

The hash (sum of char codes) is commutative — anagram pairs produce identical jitter and stack on the same point:

Pair	Hash	Real countries
AL / LA	141	Albania / Laos
CN / NC	145	China / New Caledonia
NI / IN	151	Nicaragua / India

Fix: use a position-sensitive hash:

const hash = countryCode.toUpperCase().split('')
  .reduce((acc, char) => acc * 31 + char.charCodeAt(0), 0);

The * 31 (standard string hash multiplier) makes character order matter, eliminating anagram collisions.

💡 Suggestion: All threats from same country now stack on one point

Before, Math.random() scattered multiple threats from the same country across the centroid area. Now they all resolve to the exact same [lat, lon]. If the caller ever plots multiple threats per country, they'll overlap completely.

If a per-threat identifier exists (IP hash, event ID), passing it as a second param would give deterministic per-threat jitter while still preventing re-render jumps:

function getCountryCentroid(countryCode: string, seed?: number)

If only one marker per country is expected, this is fine as-is.

💡 Suggestion: lat/lon offset correlation

hash and hash * 7 are linearly dependent — all countries' jitter falls along a narrow diagonal in 2D space rather than filling the area. Using a second independent derivation would spread better:

const latOffset = ((hash % 1000) / 1000 - 0.5) * jitterScale;
const lonOffset = (((hash >>> 8 ^ hash * 2654435761) % 1000) / 1000 - 0.5) * jitterScale;