Keep commas in search filter values - #4496

Problem

Editing a search filter initialized every string value by splitting on commas. Regex quantifiers such as {21,22} were therefore truncated in the input even though the URL parser had preserved the full expression.

Fix

Keep search-operator values as one string when initializing FilterRecord; retain comma splitting for the existing multi-value operators. Add a component regression using the reported regex shape.

User impact

Regex, contains, and other free-text filter values containing commas remain fully visible and editable instead of showing only the prefix before the first comma.

Verification

• Focused regressions: 2 passed, including an operator transition that preserves the full comma-bearing value.
• TypeScript: tsc --noEmit passed after generating the Prisma client with a placeholder local database URL.
• Biome check on both changed files passed.
• Full Vitest run: 93 files and 732 tests passed; 4 unrelated suites could not load the repository's PostCSS plugin on this Windows environment.
• Full repository lint reaches existing diagnostics outside this diff; both changed files are clean.
• git diff --check passed.

Fixes #4489

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