docs: add connection parameter reference (Thrift vs SEA/Kernel)

[eric-wang-1990]

What

Adds docs/connection-parameters.md — a single reference listing every public connection / session / per-statement parameter the Node.js connector accepts, and whether each is honored on the Thrift backend (default), the SEA / Kernel backend (useKernel: true), or both.

The goal is to make protocol support gaps explicit: a parameter honored on one backend but ignored or rejected on the other is called out in a Gap column.

Format

Modeled on the databricks-sql-kernel connection-parameters reference. Grouped by concern: connection identity · authentication · HTTP/proxy/retries · TLS/SSL · results & type rendering · session defaults · telemetry · per-statement options. Each row has a ✅ / ❌ / ⚠️ / — verdict per backend plus a Gap note.

Sources of truth

• Public option shape ← lib/contracts/IDBSQLClient.ts
• Internal / kernel-only flags ← lib/contracts/InternalConnectionOptions.ts
• Thrift wiring ← lib/DBSQLClient.ts, lib/thrift-backend/ThriftBackend.ts, lib/connection/connections/HttpConnection.ts
• Kernel wiring ← lib/kernel/KernelAuth.ts, lib/kernel/KernelBackend.ts, lib/kernel/KernelSessionBackend.ts

Notable gaps documented

Thrift-only (missing/ignored on Kernel): enableMetricViewMetadata auto-injection; auth types custom / token-provider / external-token / static-token + token federation; Azure-direct OAuth; custom OAuth persistence; custom U2M oauthClientId; SOCKS proxies; per-statement useCloudFetch / useLZ4Compression / stagingAllowedLocalPath.

Kernel-only (no Thrift public equivalent): maxConnections; all TLS controls (checkServerCertificate, checkServerCertificateHostname, customCaCert, clientCertPem, clientKeyPem).

TLS caveat surfaced: the Thrift connect() path exposes no public TLS options and hardcodes rejectUnauthorized: false (HttpConnection.ts); the internal ca/cert/key fields are never populated from a public option. TLS customization is therefore kernel-only in practice.

All kernel-path behavior reflects the M0 stub (useKernel is internal/unstable) and is noted as subject to change.

Docs-only change — no code touched.

This pull request and its description were written by Isaac.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[github-actions]

Thanks for your contribution! To satisfy the DCO policy in our contributing guide every commit message must include a sign-off message. One or more of your commits is missing this message. You can reword previous commit messages with an interactive rebase (git rebase -i main).

[msrathore-db]

Thanks!