Release Note 26.2.0

## Features & Improvements

1. Support snapshot, incremental, and initial scan modes for Doris Source (#679
(https://github.com/apache/doris-flink-connector/pull/679))

2. Support one-way TLS connections to Doris over HTTP, MySQL/JDBC, Thrift, and Arrow Flight SQL (#686
(https://github.com/apache/doris-flink-connector/pull/686))

3. Support S3 TVF sink write mode (#688 (https://github.com/apache/doris-flink-connector/pull/688))
4. Add JDK 21 build and CI validation for Flink 2.x (#678
(https://github.com/apache/doris-flink-connector/pull/678))

5. Report standard FLIP-33 sink metrics numRecordsSend and numBytesSend (#681
(https://github.com/apache/doris-flink-connector/pull/681))

6. Support PostgreSQL regclass type in CDC synchronization (#658
(https://github.com/apache/doris-flink-connector/pull/658))

7. Add Doris regression test programs (#687 (https://github.com/apache/doris-flink-connector/pull/687))

## Bug Fixes

1. Fix oversized checkpoint state for initial snapshots of large tables (#690
(https://github.com/apache/doris-flink-connector/pull/690))

2. Fix DorisWriter aborting the wrong transaction (#683
(https://github.com/apache/doris-flink-connector/pull/683))

3. Fix MongoDB CDC parsing when fullDocument is returned as a JSON string (#671
(https://github.com/apache/doris-flink-connector/pull/671))

4. Fix Arrow timestamp conversion for Doris DATETIME and TIMESTAMPTZ types (#676
(https://github.com/apache/doris-flink-connector/pull/676))

## Thanks

@Cq-study
@JNSimba
@liujiwen-up
@Sbaia
@Tan-JiaLiang
@ziyanTOP

The issue body provides the proposed 26.2.0 release-note content, including features, bug fixes, and contributors, but names no target file or test. First locate the repository's release-note convention and the document for version 26.2.0. Done means the listed changes and acknowledgements are captured in the expected release documentation.

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