Add native CockroachDB connector support

[viragtripathi]

Summary

Implements full CockroachDB integration as a source peer, following the same patterns as existing PostgreSQL and MySQL connectors.

What's included

Backend:

• Native Go connector (490 lines) using pgx driver with CockroachDB-specific configuration
• Schema introspection: GetSchemas, GetTables, GetColumns
• Connection support for local and cloud deployments
• TLS support (disabled by default for easier local development, matching Postgres behavior)
• SSH tunnel support in backend (intentionally no UI - CockroachDB Cloud doesn't need SSH)
• Version validation and variant detection (Cloud/Dedicated/Serverless)
• Rust analyzer and catalog support for peer configuration

Frontend:

• Complete UI integration for peer creation
• Form validation and field helpers
• CockroachDB logo and proper display names

Testing performed

• ✅ UI peer creation with form validation
• ✅ API peer creation and validation
• ✅ Local CockroachDB connection (insecure mode)
• ✅ Cloud CockroachDB connection (with TLS)
• ✅ Schema introspection

Design Decisions

TLS Default: Set to false (matching Postgres) for easier local development. Cloud users will enable it as needed.

SSH Support: Backend implementation included but no UI exposed. CockroachDB Cloud deployments (primary use case) don't require SSH tunnels, keeping the UI simpler and more focused.

Note on SQL syntax

SQL syntax support (CREATE PEER FROM COCKROACHDB) requires updates to the sqlparser dependency and will be added in a follow-up PR.

Files changed

23 files changed, 936 insertions(+), 2 deletions(-)

[CLAassistant]

All committers have signed the CLA.

[viragtripathi]

Rebased onto current main and expanded this from a peer-only connector to a full source integration:

• CREATE PEER ... FROM COCKROACHDB now goes through the in-tree parser (following Drop sqlparser-rs (0.45) fork in favor of upstream (0.61) #4145), so the sqlparser fork dependency is gone and I am closing Add CockroachDB PeerType support sqlparser-rs#39
• QRep replication using AS OF SYSTEM TIME partitioned reads with watermark based partitioning
• CDC via sinkless changefeeds: resolved timestamp checkpoints, cursor resume with backoff, gapless snapshot handoff via cluster_logical_timestamp(), delete key fallback from the changefeed message key, replay dedup, and SQLSTATE based error classification. Changefeed webhook sink support is a natural follow-up for higher throughput deployments.
• Unit tests, an e2e suite, and a CockroachDB service container wired into CI, plus Tilt dev environment wiring matching the other source databases

Tested against CockroachDB v25.4.13 (e2e suite, single node insecure) and a CockroachDB Cloud v26.2.1 cluster over verify-full TLS for connectivity, validation and schema introspection. A docs PR to peerdb-io/docs will follow once this merges.

[viragtripathi]

Updated: the rangefeed validation check queried crdb_internal.cluster_settings, which is gated behind allow_unsafe_internals from v26.1 onward, so on newer clusters the check silently returned nothing and mirror validation passed without verifying rangefeeds. Switched it (and the database variant lookup) to SHOW CLUSTER SETTING, which only needs VIEWCLUSTERSETTING, and added an e2e test covering the rangefeed validation path against a live cluster, including the disabled-setting error case.

Planned follow-ups: changefeed sink transports (webhook and Kafka) for deployments that need changefeed job semantics, protected timestamps through large initial scans, and DB Console metrics. The changefeed envelope parsing and checkpointing in this PR are transport independent, so those land as additional transports rather than a redesign.

[viragtripathi]

Continued in #4662 from an in repo branch so CI runs without the external contributor approval gate. Same five commit stack, no code changes.