cleanup: remove dead code, drop unused deps, refactor derived-state effects

Lint went from 84 problems to 0. Build passes.

Dead code:
- TeamInvoices: drop the orphaned Subcontractor PO block (updateSubcontractorPO
  plus send/ready-to-pay/paid/reopen/cancel/delete/download/CPA-export handlers
  and ~25 derived vars). That feature moved to the routed
  TeamCreateSubcontractorPO / TeamSubcontractorPODetail pages in the Layout2
  redesign; these were leftovers. 2100 -> 1880 lines.
- Tasks: drop unrendered project sort/tab/completion logic in TasksPageShell.
- Remove 59 unused vars, imports, and handlers across 12 other files.

Removed wasted queries:
- TeamInvoices ran a nested subcontractor_payments join (profiles, projects,
  companies, PO items, tasks) on every page load into state nothing read.
- TeamInvoices and ExternalMyInvoices each fetched a task-type map on invoice
  open and discarded it; the ExternalMyInvoices one blocked the detail popup.
- RequestForm queried sign_families on mount into unread state.

Dependencies:
- Drop heic2any (zero imports). heic-to is the one in use and already lazy-loads.

Effects and exports:
- RequestForm: remove 4 effects. Sign-row sizing and company-change resets move
  into their change handlers; single-company selection is derived during render
  rather than written back into form state.
- FilterDropdown: measure position on click instead of in an effect, which also
  removes a one-frame stale-position flicker.
- BrandBook: latest-ref pattern so the 900ms address debounce is not reset by
  handler identity.
- ClientMyInvoices: hoist MONTHS to module scope.
- Split non-component exports: POPUP_FIELD_LABEL moves to lib/popupStyles.js;
  resolveProfileAvatar and useLiveClock are internal-only; getGreeting deleted
  as nothing referenced it.

Companies.jsx keeps one scoped eslint-disable with a reason: load() only
setStates after awaiting its queries, so set-state-in-effect is a false positive
there, and load() is shared with the create/delete handlers.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/pages/BrandBook.jsx

@@ -159,7 +159,6 @@ export default function BrandBook() {
   const projectLogoRef = useRef();
   const clientLogoRef = useRef();
   const [filterCompany, setFilterCompany] = useState('');
-  const [selectedBookIds, setSelectedBookIds] = useState([]);
   const { sortKey: bbSortKey, sortDir: bbSortDir, toggle: bbToggle, sort: bbSort } = useSortable('updated_at');
 
   useEffect(() => {
@@ -175,7 +174,8 @@ export default function BrandBook() {
 
     const timeoutId = setTimeout(() => {
       if (address.includes(',') && address.length >= 12) {
-        loadMapsFromAddress(address, { silent: true });
+        // Called through a ref so the debounce isn't reset by the handler's identity.
+        loadMapsFromAddressRef.current(address, { silent: true });
       }
     }, 900);
 
@@ -222,7 +222,6 @@ export default function BrandBook() {
     setLoadingBooks(true);
     const { data } = await supabase.from('brand_books').select('*').order('updated_at', { ascending: false });
     setSavedBooks(data || []);
-    setSelectedBookIds(prev => prev.filter(id => (data || []).some(book => book.id === id)));
     setLoadingBooks(false);
   };
 
@@ -235,6 +234,8 @@ export default function BrandBook() {
     setBookInfo(b => ({ ...b, revision: normalizeRevision(b.revision) }));
   };
 
+  const loadMapsFromAddressRef = useRef(null);
+
   const loadMapsFromAddress = async (address = bookInfo.customerAddress, { silent = false, feature = null } = {}) => {
     const trimmed = String(address || '').trim();
     if (!trimmed) {
@@ -290,6 +291,10 @@ export default function BrandBook() {
     }
   };
 
+  useEffect(() => {
+    loadMapsFromAddressRef.current = loadMapsFromAddress;
+  });
+
   const handleCustomerAddressChange = (e) => {
     const value = e.target.value;
     setBookInfo(b => ({ ...b, customerAddress: value, siteAddress: value }));