docs(temporal) WB-529 submission test plan

[jimmeryn]

What

• packages/temporal/TESTING.md — test plan: replay safety, limitations, suite/CI table
• Cache-off replay test (maxCachedWorkflows: 0), the second side-effect technique Temporal's plugin guide names
• replay-audit.md: runtime file list corrected, resolve-start-node.ts added, Object.keys verdict fixed
• test/replay/README.md: four harness checks, not three; fan-out claim narrowed to what is true
• README.md: one-line pointer to TESTING.md

Not in scope, and why

• No stack-level e2e (HTTP → worker → Postgres). Needs its own CI job with containers; not a docs ticket
• Cancellation and node-failure paths untested in the sandbox. Disclosed in TESTING.md
• No count of audit sources in the doc. Ticket asked for "18 sources, 8 rules"; actual is 20 and 9. Counts rot in a permanent doc, so they go in the submission form instead
• Submission form not filled. Blocked on WB-521 (owner, DocuSign), WB-531 (integration guide), WB-628 (npm publish). The Documentation review area cannot be answered until the last two land
• CI re-downloads a 141 MB dev-server binary per temporal job, uncached. Separate ticket

[dawidaksamski]

This will become deprecated once WB-629 is finished 😊