fix(web): make sidebar lists, monitor panels, and Tools placeholder fill height (#1663) (#1664)

Three related "fill the available height" layout fixes to the connected screens:

- Tools & Prompts sidebars: replace the fixed magic max-height on ToolControls/
  PromptControls with the Resources pattern — sidebar Card `variant="sidebar"`
  (full-height flex column) + `Stack flex={1} mih={0}` + a flex-filling
  ScrollArea — so the list runs to the bottom of the card before scrolling.
- Logs/Console/Protocol/Network standalone screens: only override ScreenLayout
  `h` when embedded. Passing `h={undefined}` clobbered the default
  `h: calc(100dvh - header)` (withProps plain-spreads), collapsing an empty
  screen to its controls' height. Also center the Network/Protocol empty states.
- Tools placeholder: render the "Select a tool" empty state in a full-height
  `DetailCard flex={1}` (like Prompts/Resources) instead of the content-sized
  preview card, so it fills the pane.


Claude-Session: https://claude.ai/code/session_015sMW1YZXkM7fDkdPtHpE95

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/web/src/components/screens/PromptsScreen/PromptsScreen.tsx

@@ -69,9 +69,13 @@ const Sidebar = Stack.withProps({
   flex: "0 0 auto",
 });
 
+// `sidebar` variant makes the card a full-height flex column capped at the
+// screen height, so PromptControls' list fills the card and scrolls internally
+// once it overflows (matching the Resources sidebar).
 const SidebarCard = Card.withProps({
   withBorder: true,
   padding: "lg",
+  variant: "sidebar",
 });
 
 const DetailCard = Card.withProps({