Add Opus 4.8 to the Claude model picker

Opus 4.8 (and its 1M-context variant) become the default Claude
models, pushing Opus 4.6 off the default slot. Opus 4.7 stays in
the list as the previous release.

packages/cli/tests/15-provider.test.ts

@@ -45,6 +45,16 @@ interface ProviderListRow {
 }
 
 const EXPECTED_CLAUDE_MODELS = [
+  {
+    id: "claude-opus-4-8[1m]",
+    model: "Opus 4.8 1M",
+    descriptionFragment: "1M context window",
+  },
+  {
+    id: "claude-opus-4-8",
+    model: "Opus 4.8",
+    descriptionFragment: "Latest release",
+  },
   {
     id: "claude-opus-4-7[1m]",
     model: "Opus 4.7 1M",
@@ -53,7 +63,7 @@ const EXPECTED_CLAUDE_MODELS = [
   {
     id: "claude-opus-4-7",
     model: "Opus 4.7",
-    descriptionFragment: "Latest release",
+    descriptionFragment: "Previous release",
   },
   {
     id: "claude-opus-4-6[1m]",