docs(auth): require caller credentials for stream data requests

[NathanFlurry]

Summary

Document caller credentials for stream data requests and the distinction between public stream authority and internal service credentials. Stacked on actor route reconciliation #19.

[NathanFlurry]

Stack for rivet-dev/rivet-durable-streams

• #18 feat(auth): enforce caller credentials and trusted stream wa …
• #20 docs(auth): require caller credentials for stream data reque … 👈
• #19 feat(subscriptions): reconcile declarative actor stream rout …
• #17 feat(subscriptions): authenticate trusted Rivet gateway deli …
• #21 feat: add durable webhook and pull-wake subscriptions
• main

Get stack: forklift get 20
Push local edits: forklift submit
Merge when ready: forklift merge 20

_{change nsrtwvuv}