feat: full mobile responsive optimization for Android/iPhone

- Add bottom navigation bar (6 tabs) for mobile, hidden on desktop
- Compact header with smaller logo and reduced padding on mobile
- Collapsible filter bar with active filter count badge on mobile
- Bottom-sheet style dropdowns with overlay and larger touch targets
- Fullscreen AI chat on mobile, floating window on desktop
- Responsive dashboard cards with always-visible expand button
- Smaller table text and touch-friendly scroll on all data grids
- iPhone safe-area support and thinner scrollbars on mobile

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

components/WeeklyGrid.tsx

@@ -632,9 +632,9 @@ const WeeklyGrid: React.FC<WeeklyGridProps & { top50Mode: 'eu' | 'uk' }> = ({
     }, [sortedRows, allWeeks, weekTotals]);
 
     return (
-        <div className="flex flex-col gap-4 animate-fade-in">
+        <div className="flex flex-col gap-3 md:gap-4 animate-fade-in px-1 md:px-0">
             {/* Toolbar: Search & Pagination */}
-            <div className="flex flex-col lg:flex-row justify-between items-center gap-4 bg-slate-900 border border-white/10 p-4 rounded-xl shadow-lg">
+            <div className="flex flex-col lg:flex-row justify-between items-center gap-3 md:gap-4 bg-slate-900 border border-white/10 p-2 md:p-4 rounded-xl shadow-lg">
                 <div className="flex flex-wrap items-center gap-4 w-full lg:w-auto">
                     {/* Search Input */}
                     <div className="relative w-full md:w-80">
@@ -739,8 +739,8 @@ const WeeklyGrid: React.FC<WeeklyGridProps & { top50Mode: 'eu' | 'uk' }> = ({
             </div>
 
             <div className="bg-slate-900 border border-white/10 rounded-xl overflow-hidden shadow-2xl flex-1 min-h-0">
-                <div className="overflow-x-auto overflow-y-auto h-full max-h-[calc(100vh-220px)] custom-scrollbar">
-                    <table className="w-full text-left border-collapse min-w-[max-content]">
+                <div className="overflow-x-auto overflow-y-auto h-full max-h-[calc(100vh-220px)] custom-scrollbar scroll-touch">
+                    <table className="w-full text-left border-collapse min-w-[max-content] text-[10px] md:text-sm">
                         <thead className="sticky top-0 z-20 bg-slate-900">
                             <tr className="bg-slate-900 border-b border-white/10 relative z-30">
                                 <th