refactor(search): extract ChipType to chip-types.ts; audit NL fixtures

Pre-implementation step for #743: ChipType union extracted from
InterpretationChipRow and +page.svelte into shared chip-types.ts;
resolvedTags/tagsApplied neutral defaults added to test fixtures.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/search/InterpretationChipRow.svelte.spec.ts

@@ -17,8 +17,10 @@ const makeInterpretation = (
 	resolvedPersons: [],
 	ambiguousPersons: [],
 	keywords: [],
+	resolvedTags: [],
 	rawQuery: 'test',
 	keywordsApplied: true,
+	tagsApplied: false,
 	...overrides
 });