frontend: apply tanstack router best practices

[malinskibeniamin]

TanStack Router - Expand validateSearch for Type Safety

Summary

This PR replaces raw URLSearchParams usage with route-level validateSearch + Zod schemas for type-safe search params across the Redpanda Console frontend.

Changes

Routes with validateSearch Added

Route	Search Params	Schema
/groups/$groupId	q, withLag	String search, boolean filter
/connect-clusters/	defaultTab	Enum: kafka-connect, redpanda-connect, redpanda-connect-secret
/topics/	pageSize, page	Pagination integers
/topics/$topicName/	pageSize, page	Pagination integers
/rp-connect/$pipelineId/	pageSize, page	Pagination integers
/connect-clusters/$clusterName/$connector	pageSize, page	Pagination integers
/transforms/$transformName	pageSize, page	Pagination integers

Pagination Hook Refactor

• use-pagination-params.ts: Migrated from raw URLSearchParams to nuqs with parseAsInteger
• use-pagination-params.test.tsx: Updated to use NuqsTestingAdapter for proper testing

Component Refactors

• group-details.tsx: Now accepts search and onSearchChange props instead of using queryToObj/editQuery
• overview.tsx (connect): Now accepts defaultTab as prop instead of parsing URL manually
• login.tsx: Fixed to use searchStr instead of search for raw URL string access
• login-complete.tsx: Replaced deprecated queryToObj with native URLSearchParams

Deprecations

Added @deprecated JSDoc comments to src/utils/query-helper.ts:

• queryToObj() → Use useSearch() hook
• objToQuery() → Use navigate({ search: ... })
• editQuery() → Use navigate({ search: (prev) => ... })

Files Modified

src/routes/groups/$groupId.tsx
src/routes/connect-clusters/index.tsx
src/routes/topics/index.tsx
src/routes/topics/$topicName/index.tsx
src/routes/rp-connect/$pipelineId/index.tsx
src/routes/connect-clusters/$clusterName/$connector.tsx
src/routes/transforms/$transformName.tsx
src/components/pages/consumers/group-details.tsx
src/components/pages/connect/overview.tsx
src/components/misc/login.tsx
src/components/misc/login-complete.tsx
src/hooks/use-pagination-params.ts
src/hooks/use-pagination-params.test.tsx
src/utils/query-helper.ts

Verification

• ✅ bun run type:check - Passes
• ✅ bun run lint - Passes (exit code 0)
• ✅ bun run test - All 358 tests pass
• ✅ bun run build - Successful

Migration Path

Routes already using validateSearch (unchanged): 10 routes in security, schema-registry, rp-connect, mcp-servers, and agents.

Routes using nuqs hooks (unchanged): acl-list, topic-list, schema-list, Tab.Messages, transcript components, and preview hooks.

Remaining files using deprecated editQuery (future work):

• src/components/pages/topics/topic-list.tsx
• src/components/pages/consumers/group-list.tsx
• src/components/pages/topics/tab-partitions.tsx
• src/components/pages/topics/tab-consumers.tsx