Correct the misspelled achievement telemetry event schema

[Exohayvan]

Summary

All Minecraft loaders emit the progression event name achevement_earned instead of achievement_earned.

Evidence

• Each loader's ModAnalytics.java defines the same misspelled event constant.
• No loader emits the correctly spelled name.
• Existing dashboards or queries using the expected schema will not include these events.

Impact

Progression telemetry is stored under an unexpected event name, and a simple rename later can split historical and new data unless migration/alias behavior is deliberate.

Reproduction / verification

• Capture an advancement event through a test analytics client.
• Verify the canonical event name and compatibility treatment for historical data.

Proposed direction

Adopt achievement_earned as the canonical schema and document a migration, alias, or dashboard transition for historical achevement_earned data.

Acceptance criteria

• All loaders emit one correctly spelled canonical event.
• Historical analytics continuity is explicitly handled.
• Schema tests prevent future spelling drift.

Audit provenance

Candidate #31 from the read-only repository audit performed on 2026-07-20. This is separate from existing issues #3, #4, #25, and #27 unless explicitly linked later.