fix: use CSS Grid for mobile terminal layout

Replace flexbox chains with CSS Grid to give content area definite height:
- grid-template-rows: auto 1fr auto for header/content/keys
- Use 100dvh for proper mobile viewport handling
- Terminal fills content area with position: absolute
- Remove mobile-terminal-shell wrapper (redundant)
- Content area gets real height from grid, fixing FitAddon calculations

apps/web/src/styles.css

@@ -3062,15 +3062,15 @@ a.nav-item,
    Mobile Terminal Styles
    ============================================ */
 
-.mobile-terminal-shell {
-  height: 100vh;
-  overflow: hidden;
-}
-
-.mobile-terminal-wrapper {
-  display: flex;
-  flex-direction: column;
+ .mobile-terminal-wrapper {
+  display: grid;
+  grid-template-rows: auto 1fr auto;
+  grid-template-areas:
+    "header"
+    "content"
+    "keys";
   height: 100vh;
+  height: 100dvh; /* Dynamic viewport height for mobile */
   background: #1e1e1e;
   position: relative;
   overflow: hidden;
@@ -3078,13 +3078,13 @@ a.nav-item,
 
 /* Mobile Terminal Header */
 .mobile-terminal-header {
+  grid-area: header;
   display: flex;
   align-items: center;
   justify-content: space-between;
   padding: var(--space-2) var(--space-3);
   background: #2d2d2d;
   border-bottom: 1px solid #3e3e3e;
-  flex-shrink: 0;
   transition: transform 0.3s ease, opacity 0.3s ease, height 0.3s ease, padding 0.3s ease, margin 0.3s ease;
   z-index: 100;
   overflow: hidden;
@@ -3179,36 +3179,16 @@ a.nav-item,
 
 /* Mobile Terminal Content */
 .mobile-terminal-content {
-  flex: 1;
-  min-height: 0;
+  grid-area: content;
   overflow: hidden;
   position: relative;
-  display: flex;
-  flex-direction: column;
+  background: #1e1e1e;
 }
 
-/* Terminal wrapper - explicit height for xterm.js */
+/* Terminal wrapper - fills content area */
 .terminal-wrapper.mobile {
   border: none;
   border-radius: 0;
-  flex: 1;
-  min-height: 0;
-  width: 100%;
-  overflow: hidden;
-  display: flex;
-  flex-direction: column;
-}
-
-.terminal-wrapper.mobile .terminal-container {
-  flex: 1;
-  min-height: 0;
-  padding: 0;
-  overflow: hidden;
-  position: relative;
-}
-
-/* Ensure xterm fills container */
-.terminal-wrapper.mobile .terminal-container .xterm {
   position: absolute;
   top: 0;
   left: 0;
@@ -3216,10 +3196,25 @@ a.nav-item,
   bottom: 0;
   width: 100%;
   height: 100%;
+  overflow: hidden;
+}
+
+.terminal-wrapper.mobile .terminal-container {
+  width: 100%;
+  height: 100%;
+  padding: 0;
+  overflow: hidden;
+}
+
+/* xterm fills container */
+.terminal-wrapper.mobile .terminal-container .xterm {
+  width: 100%;
+  height: 100%;
 }
 
 /* Special Keys Strip */
 .special-keys-strip {
+  grid-area: keys;
   display: flex;
   align-items: center;
   gap: 2px;
@@ -3229,7 +3224,6 @@ a.nav-item,
   overflow-x: auto;
   -webkit-overflow-scrolling: touch;
   scrollbar-width: none;
-  flex-shrink: 0;
   transition: transform 0.3s ease, opacity 0.3s ease;
   z-index: 100;
 }