fix(storage): honor local datasource filters

[HandSonic]

Related issue

N/A - this defect was found during review of local datasource pagination; no public issue currently tracks it.

Summary

• Apply alias search and datasource-kind filters before pagination and total calculation.
• Match the actual PRIVATE and SHARED kind codes case-insensitively.
• Treat legacy null kinds as private and handle null aliases without failing.

Affected surfaces

• Frontend / Web
• Backend / API / Storage
• Database plugin / Driver
• JCEF / Desktop packaging
• CI / Build / Release
• Documentation only

Verification

• Reproduced on current main: the original 3 filter tests ran with 2 failures (name and kind filters ignored).
• After integration with main, storage reactor package passed: storage 65, tools 77, domain-api 27; 169 tests, zero failures/errors/skips.
• Command: mvn -B -ntp -f chat2db-community-server/pom.xml -pl :chat2db-community-storage -am -Dmaven.test.skip=false -DskipTests=false '-Dsurefire.includes=**/*Test.java' -Dsurefire.failIfNoSpecifiedTests=false -Dmaven.test.failure.ignore=false package. Test JVM home/temp directories were isolated.
• Executable backend package passed. Fresh Playwright CLI verification created four SQLite connections through the UI and checked real browser requests for case-insensitive search, both result pages, out-of-range pages, totals, empty results, blank filters and reload.
• The two PR files in the integrated head are byte-identical to the Web-tested version. New-head checks are available below.
• Scope: the Web list request exposes searchKey but does not expose kind; kind filtering is verified at the storage layer. This does not change sidebar tree search.

Risk and compatibility

• Public API or stored data: No request/response or on-disk schema changes. Existing query fields now affect local storage results as their contract requires.
• Database or driver compatibility: N/A - filtering is limited to the local datasource store.
• Network, privacy, or security: N/A - no network, credential, or password handling changes.
• Community / Local / Pro boundary: The change is confined to LocalWorkspaceStorage; other storage implementations and editions are unchanged.
• Backward compatibility: Unfiltered listing order and pagination are unchanged. Legacy records with a null kind are intentionally included by the private filter.

Reviewer map

• Reviewer: @openai0229 (default CODEOWNER for community storage).
• Start here: LocalWorkspaceStorage.listDataSources, then the three filter-focused cases in LocalWorkspaceStorageDataSourceFilterTest.
• Failure condition: Search and kind filters must be applied before slicing and total calculation; null aliases must not throw, and legacy null kinds must match PRIVATE.
• Rollback or disable path: Revert commit 7191e49bd0a96a88d1e786558bc6a54714e77147; there is no runtime flag because this makes existing request fields effective for local storage.

Contributor declaration

• I linked the Issue that defines this change. (N/A - no public issue exists.)
• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below, or this PR contains no substantial AI-generated code.

AI assistance: Substantial AI assistance was used for implementation, tests, and adversarial review; the resulting diff and test evidence were manually inspected.