fix: constrain dialog content to the viewport

- Add dynamic viewport bounds and scrollable body regions to dialogs and modals\n- Make tool-launch popups use the shared scrollable body pattern\n- Keep mobile sheets, action sheets, and notification popups scroll-contained\n- Restore the ProjectsPage test setup required for the frontend suite\n\nOpenSpec: fix-dialog-scroll-containment\nQuality gates: npm run typecheck, npm run lint, npm test (88 passed), npm run build

apps/web/src/components/features/tool/start-tool-fab.tsx

@@ -62,6 +62,7 @@ export function StartToolFAB() {
 							</button>
 						</div>
 
+						<div className="modal-body">
 						{workspacesLoading ? (
 							<p className="muted">Loading workspaces...</p>
 						) : workspaces.length === 0 ? (
@@ -110,6 +111,7 @@ export function StartToolFAB() {
 								/>
 							</>
 						)}
+						</div>
 					</div>
 				</div>
 			)}