feat(connectors): add SurrealDB source connector

[countradooku]

Description

Apache Iggy should support SurrealDB as a first-class source connector.

SurrealDB is a multi-model database with document, graph, relational, time-series, geospatial, full-text, vector, hybrid search, and realtime capabilities. Its Rust SDK supports remote connections, async querying, authentication, and live queries. SurrealDB also exposes change feeds for replaying table changes, which makes it a good fit for ingesting database changes into Iggy streams.

This issue tracks the SurrealDB source only. The SurrealDB sink is tracked separately in #3438 so the write path and read/changefeed path can be designed, reviewed, and tested independently.

Affected area / component: Connectors

Proposed solution

Add core/connectors/sources/surrealdb_source.

Expected source support:

• Remote SurrealDB endpoint configuration.
• Namespace and database selection.
• Credential fields stored as SecretString and never logged.
• polling, live, and changefeed modes where supported by SurrealDB.
• Configurable tables and custom SurrealQL query.
• Persistent connector state for cursor/versionstamp/timestamp tracking.
• Create/update/delete operation envelopes for realtime/changefeed modes.
• Configurable payload extraction and metadata wrapping.
• Payload formats: json, text, and raw where practical.
• Recovery behavior that avoids duplicate delivery where the backend exposes enough cursor information.
• Configurable batch size, poll interval, retry count, retry delay, and verbose_logging.
• Proper transient/permanent error mapping.

Implementation requirements:

• Follow existing connector layout and naming conventions.
• Keep the plugin crate as cdylib plus lib.
• Add README and example runtime config files.
• Add unit tests for config validation, payload extraction, operation envelope mapping, error classification, and state restore.
• Include the canonical source state tests expected by the connectors subsystem.
• Add Docker-backed integration tests for source polling and at least one live/query or changefeed path.
• Run cargo fmt --all, cargo sort --no-format --workspace, targeted tests, and connector-relevant CI scripts.
• Validate any new dependency through the repo's third-party license workflow before merging.

Dependency note

Use the SurrealDB Rust SDK only after confirming it is acceptable for Apache Iggy's dependency policy. Avoid embedded SurrealDB storage features unless their licensing and transitive dependencies are explicitly reviewed.

Alternatives considered

Using the existing HTTP sink or a generic HTTP polling source would not cover source state, live queries, change feeds, SurrealDB auth/session handling, operation envelopes, or recovery semantics.

Adding only a sink connector would be useful, but it would not cover SurrealDB's strongest streaming use case: moving database changes into Iggy.

[AmalenduManoj]

can i work on this

[countradooku]

I am working on this right now