refactor(telemetry): drop dead live-collector smoke and the compact/end severity probe

tests/otel.e2e.ts self-skipped on $DSH_OTLP_E2E_ENDPOINT, which nothing in
the repo sets — it never ran; the mock-collector wire spec and the keyless
Loader-composition e2e already cover the pipeline both ways.

The severityOf compact/end probe parsed another package's merged event
shape by string comparison — an untyped cross-package contract that breaks
silently — and its only consumer was the test's own stand-in declaration.
Unknown event types now uniformly fall through as info; outcome semantics
stay with the owning package.

packages/telemetry/session-telemetry/src/index.ts

@@ -44,9 +44,10 @@ declare module 'cordis' {
 /**
  * Severity of a telemetry record, pre-mapped at capture so a receiver can
  * alert with zero configuration: `error` for events whose own outcome flag
- * says so (`tool/result.isError`, `turn/end` error reasons, `compact/end`
- * errors) and for `agent-error` operational records, `warn` for
- * `prompt/blocked`, `info` for everything else.
+ * says so (`tool/result.isError`, `turn/end` error reasons) and for
+ * `agent-error` operational records, `warn` for `prompt/blocked`, `info`
+ * for everything else — including event types merged by other packages,
+ * whose outcome semantics stay with their owners.
  */
 export type TelemetrySeverity = 'info' | 'warn' | 'error'