feat: compute metering — fire-and-forget usage logging for every job

[pyramation]

Summary

Adds non-blocking compute metering so every job (inline FBP node or HTTP cloud function) writes timing and identity context to the billing tables without affecting throughput.

New module: job/worker/src/compute-meter.ts

logComputeUsage(pool, {
  jobId, taskIdentifier, databaseId, actorId, entityId,
  durationMs, status, error, payload, result,
  graphExecutionId, nodeName, dispatchType
})

Fires two async INSERTs (never awaited, errors swallowed):

1. constructive_compute_public.platform_function_invocations — detailed per-invocation record
2. constructive_usage_public.platform_usage_log_computes — billing record linked via invocation_id

Worker integration: Worker.doWork() captures process.hrtime.bigint() before execution, computes durationMs after, and calls logComputeUsage() on both the inline and HTTP paths.

Tests:

• 10 new integration tests (compute-meter.test.ts) — verify both INSERTs, correct columns, invocation linking, error resilience, duration rounding
• 6 updated inline-worker.test.ts tests — added graphCalls()/meterCalls() filters to separate graph-engine SQL from metering INSERTs

Link to Devin session: https://app.devin.ai/sessions/b2291a8e333e445aa125a2efd1996206
Requested by: @pyramation

[devin-ai-integration]

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[devin-ai-integration]

Superseded — already merged into develop via #104