Add LIKE-based CJK (Chinese, Japanese, Korean) search support for PostgreSQL, gated behind a `CJKSearch` feature flag.
PostgreSQL's built-in full-text search (`to_tsvector`/`to_tsquery`) does not support CJK languages because it relies on whitespace-based tokenization, which doesn't work for logographic/syllabic scripts that don't use spaces between words. This PR adds a `LIKE`-based fallback for search terms containing CJK characters.
**How it works:** When the `CJKSearch` feature flag is enabled and a search term contains CJK characters (Han, Hiragana, Katakana, or Hangul), the query builder generates `LIKE '%term%'` clauses instead of `to_tsvector @@ to_tsquery` expressions. Case-sensitive `LIKE` is used rather than `ILIKE` since CJK scripts have no letter casing, which also allows potential use of standard B-tree indexes.
* TestPool
* Store infra
* Store tests updates
* Bump maximum concurrent postgres connections
* More infra
* channels/jobs
* channels/app
* channels/api4
* Protect i18n from concurrent access
* Replace some use of os.Setenv
* Remove debug
* Lint fixes
* Fix more linting
* Fix test
* Remove use of Setenv in drafts tests
* Fix flaky TestWebHubCloseConnOnDBFail
* Fix merge
* [MM-62408] Add CI job to generate test coverage (#30284)
* Add CI job to generate test coverage
* Remove use of Setenv in drafts tests
* Fix flaky TestWebHubCloseConnOnDBFail
* Fix more Setenv usage
* Fix more potential flakyness
* Remove parallelism from flaky test
* Remove conflicting env var
* Fix
* Disable parallelism
* Test atomic covermode
* Disable parallelism
* Enable parallelism
* Add upload coverage step
* Fix codecov.yml
* Add codecov.yml
* Remove redundant workspace field
* Add Parallel() util methods and refactor
* Fix formatting
* More formatting fixes
* Fix reporting
