Use canonical product key for browser logs

[sarthakagrawal927]

Change

Replace only the browser logger public-key literal with the already configured pageview tracker key, verified as active production for this canonical catalog project, workspace and exact origin. No event behavior or endpoint changes. Existing historical logs remain intact.

Verification

• Bounded read-only production scope query passed with zero rows written.
• node --check public/app-health-log.js passed.
• git diff --check passed.
• Root reviewed the one-line diff; exact-head CI is required before merge.
• Guarded release and live byte/source verification follow merge.

Closes #118

Keep App Health issue 96 open for end-to-end report qualification.