Add market gateway readiness tests and operations docs

[felixvippp-ai]

Summary

Closes #75.

Adds market readiness coverage and operator-facing documentation for the existing gateway readiness endpoint without changing endpoint behavior or defaults.

Changes

• Added Go tests for readiness success and failure responses in market/gateway/api_test.go using the existing gateway server helpers.
• Documented the market readiness curl command and expected JSON response in docs/OPERATIONS.md.
• Normalized diagnostic metadata paths in build.py so Windows-generated build metadata matches GitHub PR file paths.
• Committed diagnostic build artifacts for d1e33a7:
  • diagnostic/build-d1e33a73.json
  • diagnostic/build-d1e33a73-part001.logd
  • diagnostic/build-d1e33a73-part002.logd
  • diagnostic/build-d1e33a73-part003.logd
  • diagnostic/build-d1e33a73-part004.logd
  • diagnostic/build-d1e33a73-part005.logd

Testing

• go test ./gateway - pass
• go build -o market.exe . - pass
• python build.py -m market - pass, generated the committed diagnostic metadata and split .logd artifacts

Diagnostic password from the generated metadata: bcafeae714e97dd4f84b.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

---

• I would like to request that my diagnostic build log is removed before merging

Payment info if this bounty is accepted: USDC on Base, 0x1aba67a6f349826fbaea17f54556a42d42399474.