chore: fix build warnings, add deployment config, and cleanup lint errors

- Fix React Hook dependencies and Image optimization warnings
- Add DATA_DIR and INITIAL_PASSWORD env var support
- Fix Tailwind v4 legacy syntax and suppress CSS directives warnings
- Add PropTypes and remove unused variables

src/app/landing/components/HowItWorks.js

@@ -13,7 +13,7 @@ export default function HowItWorks() {
         
         <div className="grid grid-cols-1 md:grid-cols-3 gap-8 relative">
           {/* Connection line */}
-          <div className="hidden md:block absolute top-12 left-[16%] right-[16%] h-[2px] bg-gradient-to-r from-gray-700 via-[#f97815] to-gray-700 -z-10"></div>
+          <div className="hidden md:block absolute top-12 left-[16%] right-[16%] h-[2px] bg-linear-to-r from-gray-700 via-[#f97815] to-gray-700 -z-10"></div>
           
           {/* Step 1: CLI & SDKs */}
           <div className="flex flex-col gap-6 relative group">

src/app/landing/components/Navigation.js

@@ -11,7 +11,7 @@ export default function Navigation() {
       <div className="max-w-7xl mx-auto px-6 h-16 flex items-center justify-between">
         {/* Logo */}
         <div className="flex items-center gap-3 cursor-pointer" onClick={() => router.push("/")}>
-          <div className="size-8 rounded bg-gradient-to-br from-[#f97815] to-orange-700 flex items-center justify-center text-white">
+          <div className="size-8 rounded bg-linear-to-br from-[#f97815] to-orange-700 flex items-center justify-center text-white">
             <span className="material-symbols-outlined text-[20px]">hub</span>
           </div>
           <h2 className="text-white text-xl font-bold tracking-tight">9Router</h2>