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-otel/tests/otel.e2e.ts

@@ -1,25 +0,0 @@
-/**
- * Keyless-self-skipping smoke: ship one real session's records to a live
- * OTLP collector named by $DSH_OTLP_E2E_ENDPOINT and require the SDK's
- * shutdown (flush-and-quiesce) to resolve. Skipped without the endpoint so
- * secretless CI stays green — a CI accommodation, not a cost signal.
- */
-
-import { describe, expect, it } from 'vitest'
-import { Context } from 'cordis'
-import SessionStore, { SessionId } from '@deepseek-ai/dsh-session'
-import TelemetryOtel from '../src/index.ts'
-
-describe.skipIf(!process.env.DSH_OTLP_E2E_ENDPOINT)('telemetry-otel e2e (live collector)', () => {
-  it('exports a session and quiesces cleanly', async () => {
-    const ctx = new Context()
-    await ctx.plugin(SessionStore)
-    const fiber = await ctx.plugin(TelemetryOtel, {
-      exporter: { url: process.env.DSH_OTLP_E2E_ENDPOINT! },
-    })
-    const session = ctx.sessions.create(SessionId(`e2e-${Date.now()}`), { meta: {} })
-    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
-    session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
-    await expect(fiber.dispose()).resolves.not.toThrow()
-  })
-})