fix: error-only Sentry telemetry, storm-proof capture, and crash fixes (#476)

Removes Sentry tracing entirely (BullMQ idle polling burned 4.8M transactions in 2 days at the baked 0.1 rate), decouples PostHog sampling, and replaces the type-only error scrub with a vetted-field sanitizer plus SafeError/ToolInputError contracts. One classified capture path with per-signature throttles and a per-process ceiling makes storms impossible (NODE-1E was 4,541 events from one 30s loop). Browser errors move to a dedicated web Sentry project with their own source maps. Adds the SNAPOTTER_TELEMETRY runtime kill switch and silences test fleets.

Crash fixes: remote 204/304 SSRF process kill (NODE-20), conversion-preset boot crash loop (NODE-21), Redis version preflight + unhandled subscribe rejection (NODE-1T), Sign PDF on plain-http origins (NODE-1K/1M), wavesurfer/pdf.js teardown rejections (NODE-1P/1N), bundle-import ZlibError to 400 (NODE-1Z), chart-maker input errors declassified (NODE-1H/1J), asset requests skip the session DB lookup (NODE-1D).

tests/e2e-analytics/analytics-toggle.spec.ts

@@ -23,7 +23,8 @@ interface AnalyticsConfig {
   posthogApiKey: string;
   posthogHost: string;
   sentryDsn: string;
-  sampleRate: number;
+  sentryDsnWeb: string;
+  posthogSampleRate: number;
   instanceId: string;
 }
 
@@ -87,7 +88,8 @@ test.describe("Analytics opt-out toggle", () => {
       posthogApiKey: "",
       posthogHost: "",
       sentryDsn: "",
-      sampleRate: 0,
+      sentryDsnWeb: "",
+      posthogSampleRate: 0,
       instanceId: "",
     });