(via api-Hypernova): Fix trace hierarchy by using subscribeCtx in SubscribeEnvelopes call

[macroscopeapp]

Macroscope: Fix It For Me

• This PR originated from this comment in Add APM support to XMTPD #1589.
• Since auto-merge is on, Macroscope will merge this PR after waiting for checks to pass.
• If you'd rather not wait, you can always merge this yourself but no further action from you is currently needed.
• You can also @mention Macroscope in this PR to request further changes.

Activity

Currently: Merged by api-Hypernova

Previously

• Not merged: conflicts
• Waiting on checks
• Not merged: conflicts
• Waiting on checks
• Not merged: conflicts
• Waiting on checks
• Encountered unknown error
• Action failed: Test
• Waiting on checks
• Action failed: Lint
• Waiting on checks
• Action failed: Lint
• Waiting on checks
• Action failed: Lint
• Waiting on checks
• Action failed: Lint
• Waiting on checks
• Pushed 3c6e6ef

---

Use subscribeCtx for client.SubscribeEnvelopes in syncWorker.setupStream and change stable hashing to selectors.HashKey(topic.Identifier()) with tests updated to ±10% tolerance and new node order

Propagate child span context into subscription and reserved envelope storage, switch stable hashing to topic identifier, add SQL to set work_mem, enforce payer_id FKs, and migrate latest envelope tracking to a statement-level trigger.

📍Where to Start

Start with syncWorker.setupStream in service.go and sync_worker.go in sync_worker.go to see the subscribeCtx usage, then review selectors.HashKey in stable.go.

---

Macroscope summarized 24933b8.