fix(shared): normalize claude model IDs for anthropic provider (#3290)

Anthropic API accepts claude-opus-4.6 (dot format) but not
claude-opus-4-6 (dash format). Added anthropic case to
transformModelForProvider to normalize dash-format model IDs before
they reach the provider. Updated model config snapshots and test
expectations to match the new dot-format output.

🤖 Generated with OhMyOpenCode assistance
https://github.com/code-yeongyu/oh-my-opencode

src/agents/utils.test.ts

@@ -180,7 +180,7 @@ describe("createBuiltinAgents with model overrides", () => {
 
       // #then
       expect(agents.sisyphus).toBeDefined()
-      expect(agents.sisyphus.model).toBe("anthropic/claude-opus-4-6")
+      expect(agents.sisyphus.model).toBe("anthropic/claude-opus-4.6")
     } finally {
       cacheSpy.mockRestore()
       fetchSpy.mockRestore()
@@ -918,7 +918,7 @@ describe("createBuiltinAgents with requiresAnyModel gating (sisyphus)", () => {
 
       // #then
       expect(agents.sisyphus).toBeDefined()
-      expect(agents.sisyphus.model).toBe("anthropic/claude-opus-4-6")
+      expect(agents.sisyphus.model).toBe("anthropic/claude-opus-4.6")
     } finally {
       cacheSpy.mockRestore()
       fetchSpy.mockRestore()