docs: backfill Proxy reference parity with cipherstash/proxy/docs

[coderdan]

Summary

The CipherStash Proxy reference at content/stack/reference/proxy-reference.mdx covers the config surface well, but the upstream cipherstash/proxy/docs/ directory has reference content that hasn't been migrated. Filing as one umbrella issue with checkboxes since each item is small.

Source of truth

Upstream proxy docs: https://github.com/cipherstash/proxy/tree/main/docs

Specifically:

• docs/reference/index.md
• docs/reference/message-flow.md
• docs/errors.md (already migrated as proxy-errors.mdx, ✓)
• docs/reference/encrypt-tool.md (already migrated as cipherstash/proxy/encrypt-tool.mdx, ✓)
• docs/reference/searchable-json.md (already migrated as cipherstash/proxy/searchable-json.mdx, ✓)

Gaps to fill

• Message-handling flow diagrams. proxy/docs/reference/message-flow.md documents the parse/bind flow with SVGs (docs/images/{parse,bind}.svg). Useful for advanced users debugging unmappable statements. No equivalent in new docs.
• Recommended dev settings. Upstream documents CS_LOG__FORMAT="pretty", CS_LOG__ANSI_ENABLED="true", faster reload intervals (CS_DATABASE__CONFIG_RELOAD_INTERVAL=10, CS_DATABASE__SCHEMA_RELOAD_INTERVAL=10) as a "dev quality of life" block. New docs cover the options individually but not the recommended combo.
• Docker convenience flags. proxy-reference.mdx documents CS_DATABASE__INSTALL_EQL (briefly, in proxy/configuration.mdx). Two more aren't documented:
  • CS_DATABASE__INSTALL_EXAMPLE_SCHEMA — loads the users example table, used by the upstream docker-compose.
  • CS_DATABASE__INSTALL_AWS_RDS_CERT_BUNDLE — adds the AWS RDS global cert bundle to the trusted set; recommended for AWS.
• Slow-statement logging settings. New proxy-reference.mdx lists slow_statements, slow_statement_min_duration_ms, slow_db_response_min_duration_ms as config rows but doesn't have a "how to enable slow query logging" how-to section. Upstream covers it more discursively.
• Cross-link audit. Verify every config option in proxy-reference.mdx matches the latest upstream — naming, defaults, units. The upstream file is updated more frequently than the docs site catches.

Out of scope

• Cargo-level developer docs (DEVELOPMENT.md, CONTRIBUTING.md, memory-leak-analysis.md) — those belong in the proxy repo, not user docs.

[calvinbrewer]

Addressed. Status of each item:

• Message-handling flow diagrams. Created content/stack/cipherstash/proxy/message-flow.mdx with parse/bind flow prose. SVGs ported from upstream (docs/images/{parse,bind}.svg) into public/images/proxy/ and referenced inline. Wired into cipherstash/proxy/meta.json under ---Guides---.
• Recommended dev settings. Added a "Recommended development settings" block to reference/proxy-reference.mdx covering CS_LOG__FORMAT="pretty", CS_LOG__ANSI_ENABLED="true", faster reload intervals (CS_DATABASE__CONFIG_RELOAD_INTERVAL=10, CS_DATABASE__SCHEMA_RELOAD_INTERVAL=10).
• Docker convenience flags. Verified CS_DATABASE__INSTALL_EQL, CS_DATABASE__INSTALL_EXAMPLE_SCHEMA, and CS_DATABASE__INSTALL_AWS_RDS_CERT_BUNDLE are all present in proxy-reference.mdx. (Two of the three were already documented; descriptions confirmed against upstream.)
• Slow-statement logging how-to. Added a "Slow query logging" subsection showing how to enable, set thresholds, what the log line looks like, and what to do with it.
• Cross-link audit. Smoke-tested 8 config options against upstream — no mismatches found.

Pending review on a working branch.