feat: Story 9 - Remove scroll bars for cleaner UI

Implemented Story 9: Hidden Scroll Bars
- Added CSS to hide scroll bars globally while maintaining functionality
- Used scrollbar-width: none for Firefox
- Used ::-webkit-scrollbar { display: none; } for Chrome/Safari/Edge
- Set overflow-x: hidden to prevent unwanted horizontal scrolling
- Maintained full scroll functionality (mouse wheel, trackpad, keyboard)

Updated Specs
- Added Scroll Bar Styling section to UI_UX.md
- Documented cross-browser compatibility requirements
- Specified areas affected and implementation approach

Bug Fixes
- Fixed biome linting issues in App.tsx (import organization, button type)
- Applied biome formatter for consistent code style

src/App.tsx

@@ -1,88 +1,90 @@
-import { useState, useEffect } from "react";
 import { invoke } from "@tauri-apps/api/core";
 import { open } from "@tauri-apps/plugin-dialog";
+import { useEffect, useState } from "react";
 import { Chat } from "./components/Chat";
 import "./App.css";
 
 function App() {
-  const [projectPath, setProjectPath] = useState<string | null>(null);
-  const [errorMsg, setErrorMsg] = useState<string | null>(null);
+	const [projectPath, setProjectPath] = useState<string | null>(null);
+	const [errorMsg, setErrorMsg] = useState<string | null>(null);
 
-  useEffect(() => {
-    invoke<string | null>("get_current_project")
-      .then((path) => {
-        if (path) setProjectPath(path);
-      })
-      .catch((e) => console.error(e));
-  }, []);
+	useEffect(() => {
+		invoke<string | null>("get_current_project")
+			.then((path) => {
+				if (path) setProjectPath(path);
+			})
+			.catch((e) => console.error(e));
+	}, []);
 
-  async function closeProject() {
-    try {
-      await invoke("close_project");
-      setProjectPath(null);
-    } catch (e) {
-      console.error(e);
-    }
-  }
+	async function closeProject() {
+		try {
+			await invoke("close_project");
+			setProjectPath(null);
+		} catch (e) {
+			console.error(e);
+		}
+	}
 
-  async function selectProject() {
-    try {
-      setErrorMsg(null);
-      // Open native folder picker
-      const selected = await open({
-        directory: true,
-        multiple: false,
-      });
+	async function selectProject() {
+		try {
+			setErrorMsg(null);
+			// Open native folder picker
+			const selected = await open({
+				directory: true,
+				multiple: false,
+			});
 
-      if (selected === null) {
-        // User cancelled selection
-        return;
-      }
+			if (selected === null) {
+				// User cancelled selection
+				return;
+			}
 
-      // Invoke backend command to verify and set state
-      // Note: invoke argument names must match Rust function args
-      const confirmedPath = await invoke<string>("open_project", {
-        path: selected,
-      });
-      setProjectPath(confirmedPath);
-    } catch (e) {
-      console.error(e);
-      setErrorMsg(
-        typeof e === "string" ? e : "An error occurred opening the project.",
-      );
-    }
-  }
+			// Invoke backend command to verify and set state
+			// Note: invoke argument names must match Rust function args
+			const confirmedPath = await invoke<string>("open_project", {
+				path: selected,
+			});
+			setProjectPath(confirmedPath);
+		} catch (e) {
+			console.error(e);
+			setErrorMsg(
+				typeof e === "string" ? e : "An error occurred opening the project.",
+			);
+		}
+	}
 
-  return (
-    <main
-      className="container"
-      style={{ height: "100vh", padding: 0, maxWidth: "100%" }}
-    >
-      {!projectPath ? (
-        <div
-          className="selection-screen"
-          style={{ padding: "2rem", maxWidth: "800px", margin: "0 auto" }}
-        >
-          <h1>AI Code Assistant</h1>
-          <p>
-            Please select a project folder to start the Story-Driven Spec
-            Workflow.
-          </p>
-          <button onClick={selectProject}>Open Project Directory</button>
-        </div>
-      ) : (
-        <div className="workspace" style={{ height: "100%" }}>
-          <Chat projectPath={projectPath} onCloseProject={closeProject} />
-        </div>
-      )}
+	return (
+		<main
+			className="container"
+			style={{ height: "100vh", padding: 0, maxWidth: "100%" }}
+		>
+			{!projectPath ? (
+				<div
+					className="selection-screen"
+					style={{ padding: "2rem", maxWidth: "800px", margin: "0 auto" }}
+				>
+					<h1>AI Code Assistant</h1>
+					<p>
+						Please select a project folder to start the Story-Driven Spec
+						Workflow.
+					</p>
+					<button type="button" onClick={selectProject}>
+						Open Project Directory
+					</button>
+				</div>
+			) : (
+				<div className="workspace" style={{ height: "100%" }}>
+					<Chat projectPath={projectPath} onCloseProject={closeProject} />
+				</div>
+			)}
 
-      {errorMsg && (
-        <div className="error-message" style={{ marginTop: "20px" }}>
-          <p style={{ color: "red" }}>Error: {errorMsg}</p>
-        </div>
-      )}
-    </main>
-  );
+			{errorMsg && (
+				<div className="error-message" style={{ marginTop: "20px" }}>
+					<p style={{ color: "red" }}>Error: {errorMsg}</p>
+				</div>
+			)}
+		</main>
+	);
 }
 
 export default App;