fix: prevent cumulative terminal shrinkage in fullscreen mode

When switching terminal sessions in fullscreen mode, the viewport
shrank cumulatively because .terminal-wrapper uses
grid-template-rows: auto 1fr. With showControls=false, the single
child (.terminal-container) landed in the auto track instead of 1fr,
creating a feedback loop with xterm fit().

- Add .terminal-wrapper.no-controls with grid-template-rows: 1fr
  so the container fills the wrapper when the header is hidden.
- Apply no-controls class in TerminalComponent when showControls=false.
- Replace setTimeout(50) with double requestAnimationFrame in
  TerminalPage for more reliable fit() timing after tab switches.

Quality gates: tsc --noEmit (clean), pytest (208 passed, 6 pre-existing)

apps/web/src/components/terminal.tsx

@@ -568,7 +568,7 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 		};
 
 		return (
-			<div className={`terminal-wrapper ${isMobile ? "mobile" : ""}`}>
+			<div className={`terminal-wrapper ${isMobile ? "mobile" : ""} ${!showControls ? "no-controls" : ""}`}>
 				{showControls && (
 					<div className="terminal-header">
 						<div className="terminal-header-left">