feat: add Dioxus and GPUI UI prototypes for framework comparison

Dioxus (ui-dioxus/): 2,169 lines, WebView mode (same wry as Tauri),
  Catppuccin theme, 12 components, agor-core integration, compiles clean.
  Evolution path — keeps xterm.js, gradual migration from Tauri.

GPUI (ui-gpui/): 2,490 lines, GPU-accelerated rendering, alacritty_terminal
  for native terminal, 17 files, Catppuccin palette, demo data.
  Revolution path — pure Rust UI, 120fps target, no WebView.

Both are standalone (not in workspace), share agor-core backend.
Created for side-by-side comparison to inform framework decision.

ui-dioxus/src/components/terminal.rs

@@ -0,0 +1,47 @@
+/// Terminal component — demonstrates terminal rendering capability.
+///
+/// In the Tauri+Svelte app, terminals use xterm.js (Canvas addon) via WebView.
+/// Dioxus desktop also uses wry/WebView, so xterm.js embedding IS possible
+/// via `document::eval()` or an iframe. For this prototype, we render a styled
+/// terminal area showing mock output to demonstrate the visual integration.
+///
+/// A production implementation would:
+/// 1. Inject xterm.js via `with_custom_head()` in desktop Config
+/// 2. Use `document::eval()` to create/manage Terminal instances
+/// 3. Bridge PTY output from PtyManager through DioxusEventSink -> eval()
+///
+/// The key insight: Dioxus desktop uses the SAME wry/WebKit2GTK backend as
+/// Tauri, so xterm.js works identically. No Canvas addon difference.
+
+use dioxus::prelude::*;
+
+use crate::state::{TerminalLine, TerminalLineKind};
+
+#[component]
+pub fn TerminalArea(lines: Vec<TerminalLine>) -> Element {
+    rsx! {
+        div { class: "terminal-area",
+            for line in lines.iter() {
+                div { class: "terminal-line",
+                    match line.kind {
+                        TerminalLineKind::Prompt => rsx! {
+                            span { class: "terminal-prompt", "{line.text}" }
+                        },
+                        TerminalLineKind::Output => rsx! {
+                            span { class: "terminal-output", "{line.text}" }
+                        },
+                    }
+                }
+            }
+
+            // Blinking cursor
+            div { class: "terminal-line",
+                span { class: "terminal-prompt", "$ " }
+                span {
+                    style: "animation: pulse 1s step-end infinite; color: var(--ctp-text);",
+                    "\u{2588}"
+                }
+            }
+        }
+    }
+}