fix(web): keep selected search filters visible - #1685

Fixes #131

Typing into the language or repository filter hid selected entries that did not match the filter text. Keep those selections visible at the top so users can see and clear every active filter, while filtering the remaining entries normally.

Selected entries appear only once when they also match the search. Sorting now copies the list instead of mutating the caller's entries.

Validation completed before opening this PR:

• Full application tests, lint, and all four automation test scripts passed.
• Prisma migration gate and full Docker build passed.
• Regression tests pass with the fix and fail with the original implementation.

Summary by cubic

Fixes #131 by keeping selected language and repository filters visible at the top while typing, so active filters can always be seen and cleared.

• Selected entries stay pinned above search matches and appear only once when they also match or when no other entries match.
• Sorting copies the entries list instead of mutating the caller's array.
• Adds Vitest coverage for pinned selections and a changelog entry.

^{Written for commit 82ac4e2. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes
  • Selected language and repository filters now remain visible while searching available options, even when they don’t match the search text.
  • Matching selected filters appear only once, and the filter list retains its original order data.