[telemetry-sdk-node] Reject conflicting TelemetryRuntime.init configurations

[kang-heewon]

Priority: P1

Problem

Concurrent or later TelemetryRuntime.init calls silently return the first initialization promise or completed runtime even when the caller requested different service or exporter settings.

Evidence

packages/telemetry-sdk-node/src/libs/runtime.ts:61-87 returns the existing promise at lines 77-79 and existing initialized state at lines 73-75 without comparing requested configuration.

Desired outcome

Only semantically identical initialization is idempotent; conflicting bootstraps fail clearly.

Implementation path

1. Capture a canonical configuration fingerprint before initialization.
2. Permit equal repeated calls only.
3. Raise a stable conflict Problem for differing requests, including disabled/enabled modes.
4. Add concurrent and post-init conflict tests.

Acceptance criteria

• Equal configuration calls share initialization safely.
• Differing configuration never appears to succeed.
• Diagnostics identify the conflicting runtime state.

Validation

pnpm --filter @croco/telemetry-sdk-node test

Scope boundaries

Does not introduce multi-runtime telemetry support.