feat(web): render app in Circular + Models source-tree parity

- Load licensed Circular (Book/SemiBold/Bold) via @font-face and set --font-sans
  to Circular with Geist fallback, matching bud's typeface app-wide.
- Models: Cheatcode Credits is only a source for the free model (DeepSeek); every
  other model routes through a provider API key, so credits is no longer listed there.
- Enlarge the selected-source check node to bud's size.

Author: iamjr15

apps/web/public/fonts/circular/circular-400.woff2

@@ -6,6 +6,30 @@
 @source "../../../../node_modules/streamdown/dist/**/*.js";
 @source "../../../../node_modules/ai-elements/dist/**/*.js";
 
+@font-face {
+  font-family: "circular";
+  src: url("/fonts/circular/circular-400.woff2") format("woff2");
+  font-weight: 400;
+  font-style: normal;
+  font-display: swap;
+}
+
+@font-face {
+  font-family: "circular";
+  src: url("/fonts/circular/circular-600.woff2") format("woff2");
+  font-weight: 600;
+  font-style: normal;
+  font-display: swap;
+}
+
+@font-face {
+  font-family: "circular";
+  src: url("/fonts/circular/circular-700.woff2") format("woff2");
+  font-weight: 700;
+  font-style: normal;
+  font-display: swap;
+}
+
 @custom-variant dark (&:where(.dark, .dark *));
 
 .cheatcode-workspace-frame {
@@ -31,7 +55,7 @@
 @theme inline {
   --color-background: var(--background);
   --color-foreground: var(--foreground);
-  --font-sans: var(--font-geist-sans);
+  --font-sans: "circular", var(--font-geist-sans);
   --font-mono: var(--font-geist-mono);
   --color-sidebar-ring: var(--sidebar-ring);
   --color-sidebar-border: var(--sidebar-border);

apps/web/public/fonts/circular/circular-600.woff2

@@ -254,15 +254,13 @@ function modelSourceChoices(
     providers = ["deepseek"];
   }
 
-  const choices: ModelSourceChoice[] = [
-    accessState === "free"
-      ? { active: true, id: "credits", label: "Cheatcode Credits" }
-      : {
-          active: false,
-          id: "credits",
-          label: "Cheatcode Credits",
-          unavailableMessage: "Cheatcode credits are available for DeepSeek V4.",
-        },
+  // Cheatcode Credits is only a real source for the free model (DeepSeek); every other model
+  // routes through a provider/API key, so we don't list credits there at all.
+  const choices: ModelSourceChoice[] = [];
+  if (accessState === "free") {
+    choices.push({ active: true, id: "credits", label: "Cheatcode Credits" });
+  }
+  choices.push(
     ...providers.map(
       (provider): ModelSourceChoice => ({
         active: provider === model.provider && accessState === "active",
@@ -271,7 +269,7 @@ function modelSourceChoices(
         provider,
       }),
     ),
-  ];
+  );
 
   return choices.map((choice) => {
     if (!choice.provider) {
@@ -410,7 +408,7 @@ function ModelSourceList({
                   aria-hidden="true"
                   className="absolute top-[18px] -left-3.5 z-10 flex size-4 -translate-x-1/2 -translate-y-1/2 items-center justify-center rounded-full bg-[#1b1b1b] text-white"
                 >
-                  <Check aria-hidden="true" className="size-2.5" strokeWidth={2.5} />
+                  <Check aria-hidden="true" className="size-3" strokeWidth={2.5} />
                 </span>
               ) : null}
               <button