ALL-1871 PR-2: Client-side re-validation hook with live error + summary counter updates

## ALL-1871 PR-2 - Frontend: Client-side re-validation on cell edit Linear: ALL-1871 ("In-line editing of CSV data in bulk upload preview") Branch: wilbo/all-1871-client-revalidation Depends on: PR-1 merged (wilbo/all-1871-editable-preview-cells) ### What to build Add a hook that re-runs client-side validation rules whenever editedCells changes, updating validationErrors + valid/invalid/total counts live. This is FRONTEND ONLY -- no server calls for address/device validation yet (that is PR-3). ### Key files CREATE: apps/dashboard/hooks/usePreviewValidation.ts - Input: { baseRows: PreviewRow[], editedCells: Record<number, Record<string, string>>, baseValidationErrors: ValidationError[], baseValidRows: number, baseInvalidRows: number } - Output: { activeErrors: ValidationError[], validRows: number, invalidRows: number, mergedRows: PreviewRow[] } - Logic: 1. Build mergedRows by applying editedCells on top of baseRows (row 0-indexed in array but 1-indexed in ValidationError.row) 2. Re-run client-side checks on only the edited rows: - Required field check: referenceId, firstName, lastName, streetOne, city, state, postalCode must be non-empty - Email format (basic regex: /.+@.+\..+/) - Phone: allow empty or digits/hyphens/parens/spaces - manufacturerSlug: if set, must be in VALID_MANUFACTURER_SLUGS (import from shared constant or copy the list) - manufacturerSlug + systemIdentifier: both or neither 3. Merge: take baseValidationErrors, remove entries for edited rows, add new errors for those rows 4. Recompute validRows / invalidRows - NOTE: address re-validation (geocoding) is intentionally excluded here; address fields show a pending indicator until PR-3 resolves them - Debounce the re-validation 150ms so rapid typing doesn't thrash EDIT: apps/dashboard/components/pages/ConnectPage/BulkUploadTab.tsx - Import and call usePreviewValidation instead of reading validationErrors directly from previewData - Pass activeErrors, validRows, invalidRows down to PreviewTable and the summary row counts - The summary display ("N valid rows, M invalid rows") should now update in real time as the user edits EDIT: apps/dashboard/components/pages/ConnectPage/BulkUpload/PreviewTable.tsx (minor) - Accept validRows+invalidRows props if it currently reads them from previewData directly, so parent can pass live counts ### Acceptance test - User uploads a CSV with 3 validation errors (required field missing) - Preview shows "3 validation errors" - User types a value into a required-field error cell - Error count updates immediately (drops to 2) without a page reload or network request - Valid/invalid row counts in the summary update correspondingly - An already-valid cell edited to be empty turns red and the error count increases ### Does NOT include - Address/geocoding re-validation (PR-3) - manufacturerSlug server-side format checks beyond the slug whitelist - Any data sent to backend (PR-4) ### Dependencies - Depends on PR-1 merged (editedCells state + onCellEdit wiring already in BulkUploadTab) ### Tests - Unit test in hooks/usePreviewValidation.test.ts: verify required-field error cleared on edit, new error added when valid cell cleared