feat: UI polish, lint fixes, onboarding redesign, help page expansion, and test improvements

Broad update across dashboard pages, components, extensions, and lib code. Includes ESLint config additions, onboarding flow redesign, settings page refactor, help page content expansion, dead code removal, and test mock fixes. Adds dev docs and public assets.

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

components/ui/input.tsx

@@ -1,8 +1,7 @@
 import * as React from "react"
 import { cn } from "@/lib/utils"
 
-export interface InputProps
-  extends React.InputHTMLAttributes<HTMLInputElement> {}
+export type InputProps = React.InputHTMLAttributes<HTMLInputElement>
 
 const Input = React.forwardRef<HTMLInputElement, InputProps>(
   ({ className, type, ...props }, ref) => {

components/ui/textarea.tsx

@@ -1,8 +1,7 @@
 import * as React from "react"
 import { cn } from "@/lib/utils"
 
-export interface TextareaProps
-  extends React.TextareaHTMLAttributes<HTMLTextAreaElement> {}
+export type TextareaProps = React.TextareaHTMLAttributes<HTMLTextAreaElement>
 
 const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
   ({ className, ...props }, ref) => {