fix(maestro): restore sidebar footer, fix spawn modal and session card regressions

Post-React-migration regressions: spawn submit button moved to modal
footer, sidebar footer restored (help/theme/palette/status/spawn),
session card stripped of redundant Tailwind, action buttons use proper
leaf-act/leaf-actions CSS structure for hover-only visibility.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/contexts/ThemeContext.tsx

@@ -26,15 +26,23 @@ export type Palette = (typeof PALETTES)[number];
 const PALETTE_KEY = "maestro-palette";
 
 function storedTheme(): Theme | null {
-  const v = localStorage.getItem(THEME_KEY);
-  return v === "light" || v === "dark" ? v : null;
+  try {
+    const v = localStorage.getItem(THEME_KEY);
+    return v === "light" || v === "dark" ? v : null;
+  } catch {
+    return null;
+  }
 }
 
 function storedPalette(): Palette | null {
-  const v = localStorage.getItem(PALETTE_KEY);
-  return (PALETTES as readonly string[]).includes(v ?? "")
-    ? (v as Palette)
-    : null;
+  try {
+    const v = localStorage.getItem(PALETTE_KEY);
+    return (PALETTES as readonly string[]).includes(v ?? "")
+      ? (v as Palette)
+      : null;
+  } catch {
+    return null;
+  }
 }
 
 function systemPrefersLight(): boolean {
@@ -89,7 +97,7 @@ export function ThemeProvider({ children }: { children: ReactNode }) {
   }, [palette]);
 
   const setTheme = useCallback((t: Theme) => {
-    localStorage.setItem(THEME_KEY, t);
+    try { localStorage.setItem(THEME_KEY, t); } catch { /* test env */ }
     setPinnedTheme(t);
   }, []);
 
@@ -98,7 +106,7 @@ export function ThemeProvider({ children }: { children: ReactNode }) {
   }, [theme, setTheme]);
 
   const setPalette = useCallback((p: Palette) => {
-    localStorage.setItem(PALETTE_KEY, p);
+    try { localStorage.setItem(PALETTE_KEY, p); } catch { /* test env */ }
     setPaletteState(p);
   }, []);