Score extension publish events in the telemetry pipeline

Summary

Extension publishes (push + confirm) should contribute to a user's score through the telemetry pipeline, rewarding authors for publishing and maintaining extensions.

Motivation

Currently, extension scoring (lib/app/refresh-extension-score.ts) is computed by querying pull stats at score-refresh time — it rewards popularity (downloads) but not the act of publishing. Authors who publish multiple extensions or maintain frequent version updates get no direct score credit for that effort.

Publishing an extension is a meaningful contribution that should be scored alongside CLI usage and pull-based popularity.

Design sketch

• Event source: confirmPush in lib/app/confirm-push.ts (or the telemetry extension consumer) emits a scorable event when an extension version is successfully published
• Event shape: { event: "extension_publish", distinct_id: "...", properties: { username, extensionName, version } }
• Scoring: Could be handled as a new scoring group in the activity algorithm (with its own cap), or as a fixed-point award per publish
• Deduplication: Same extension + version should only score once (idempotent on reprocessing)

Open questions

• Fixed points per publish vs. scaled by some factor (e.g., first publish worth more)?
• Should this be a new group in the activity scoring algorithm or a separate contribution type?
• Should version updates score the same as initial publishes?
• Relationship to #227 (award events) — could extension publishes just be a specific kind of award?