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/styles.css

@@ -2562,6 +2562,13 @@ a.nav-item,
 	background: #1e1e1e;
 }
 
+/* When controls are hidden (fullscreen), only the container is in flow;
+   force it into the 1fr track so it fills the wrapper instead of landing
+   in the auto track and shrinking on each fit(). */
+.terminal-wrapper.no-controls {
+	grid-template-rows: 1fr;
+}
+
 .terminal-header {
 	display: flex;
 	justify-content: space-between;