Integrate Sentry/GlitchTip error tracking with plugin-aware grouping

[tayebmokni]

Summary

Integrate Sentry-protocol error tracking (default backend recommendation: GlitchTip self-host; Sentry self-hosted also supported). Captures recovered panics, slog.Error lines with an err attribute, plugin traps with WASM-specific tags, and front-end uncaught errors / rejected promises.

Design reference

• docs/10-observability.md §8 (Error tracking)

Acceptance criteria

• github.com/getsentry/sentry-go wired; enabled when SENTRY_DSN or GLITCHTIP_DSN env var set
• Custom slog.Handler mirrors ERROR lines with err attribute to Sentry
• Recovered panic middleware captures with trace_id and request_id tags
• Plugin error capture with tags: plugin.slug, plugin.version, hook.name, wasm.trap.kind, wasm.fuel_used, wasm.fuel_remaining, wasm.memory_pages
• Plugin fingerprint override: plugin:<slug>:<trap-kind> (one issue per failure mode)
• DB error fingerprint includes query_name not raw SQL
• before_send hook re-runs PII redactor on exception extras
• Rate-limited per (plugin, trap-kind) at 1/s
• attach_stacktrace: true, send_default_pii: false
• Next.js error tracking via @sentry/nextjs for both public + admin
• Source maps: hidden-source-map for Next builds, uploaded then deleted from public bundle

Dependencies

#145, #186

Complexity

M

[tayebmokni]

Closing — shipped in the final-wave PR (#487-#492). Auto-close only fires for first ref.