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/styles/utilities.css

@@ -2328,8 +2328,10 @@ a.nav-item,
 	width: 100%;
 	max-width: 600px;
 	max-height: 70vh;
+	max-height: 70dvh;
 	display: flex;
 	flex-direction: column;
+	min-height: 0;
 	animation: slide-up 0.2s ease-out;
 }
 
@@ -2365,8 +2367,12 @@ a.nav-item,
 }
 
 .mobile-bottom-sheet-content {
+	flex: 1;
+	min-height: 0;
 	padding: 8px 0;
 	overflow-y: auto;
+	overscroll-behavior: contain;
+	-webkit-overflow-scrolling: touch;
 }
 
 .mobile-bottom-sheet-item {
@@ -3240,7 +3246,10 @@ a:active,
 	width: 100%;
 	max-width: 500px;
 	max-height: 80vh;
+	max-height: 80dvh;
 	overflow-y: auto;
+	overscroll-behavior: contain;
+	-webkit-overflow-scrolling: touch;
 	animation: slideUp 0.3s ease;
 	padding-bottom: env(safe-area-inset-bottom, 0);
 }
@@ -3602,6 +3611,7 @@ a:active,
 		max-width: none;
 		border-radius: 12px;
 		max-height: 70vh;
+		max-height: 70dvh;
 	}
 }