fix(ngmp): correct stats and media upload caching

[tintinhamans]

Player stats:

After a match, the client did not refresh its cached stats. The next match started from the same old values and submitted them as the new totals.

For example:

• The cache contains 10 wins.
• Match one submits 11 wins.
• The cache still contains 10 wins.
• Match two also submits 11 wins.
• The correct total should be 12 wins.

This could also lose rank progress. A player could earn the 5 points needed for Corporal, but a later update could still be based on the old 4-point Private stats.

The client now refreshes the cache after a successful update. It also ignores old request results when a newer request has already updated the cache.

---

Screenshots and replays:

Match-end media and upload URLs did not record which match they belonged to.

For example:

Screenshot data: match 101
Upload URL: https://uploads.example.invalid/matches/100/score.png

The same issue applied to replays:

Replay data: match 202
Upload URL: https://uploads.example.invalid/matches/201/replay.rep

The client now stores a match ID alongside both the media data and its upload URL. The client uploads them only when both IDs match.

---

Other changes:

• Checks whether cached stats are still fresh.
• Keeps the last known stats available during a refresh.
• Validates batch results before caching them.
• Limits the size of the stats cache.
• Initializes NGMP Elo fields to safe empty values.

[github-actions]

⚠️ Title/Commit Validation Failed

Invalid PR title:

• fix(ngmp): correct stats and media upload caching

Invalid commit messages:

• fix(ngmp): correct stats and upload caches
  PR titles and commit messages must follow conventional commits format:

type: Description
type(scope): Description

Allowed types: bugfix, build, chore, ci, docs, fix, feat, perf, refactor, revert, style, test, tweak, unify

See CONTRIBUTING.md for details.