fix: show Anthropic Opus 4.7+ thinking (#26026)

## Summary

- Updates Coder's pinned `github.com/coder/fantasy` fork to include
coder/fantasy#39.
- Exposes Anthropic `thinking_display` as a typed chat model provider
option with `summarized` and `omitted` values.
- Validates configured `thinking_display` values and maps them to
`fantasyanthropic.ProviderOptions.ThinkingDisplay`.
- Regenerates the API/UI option schemas so the admin model config form
gets a generated select field.

## Tests

- `go mod tidy`
- `make gen`
- `go test ./codersdk ./coderd/x/chatd/chatprovider ./coderd -run
'TestChatModelProviderOptions|TestAnthropicThinkingDisplayFromChat|TestProviderOptionsFromChatModelConfig_AnthropicThinkingDisplay|TestMergeMissingProviderOptions_AnthropicThinkingDisplay|TestValidateChatModelProviderOptions_AnthropicThinkingDisplay'`
- `go test ./coderd/x/chatd/... ./codersdk`
- `go test ./coderd -run
'TestValidateChatModelProviderOptions_AnthropicThinkingDisplay'`
- `pnpm --dir site exec -- biome lint --error-on-warnings
src/api/chatModelOptionsGenerated.json src/api/typesGenerated.ts`
- pre-commit hook, including fmt, lint, and slim build

> Mux working on behalf of Mike.

go.mod

@@ -94,8 +94,9 @@ replace github.com/spf13/afero => github.com/aslilac/afero v0.0.0-20250403163713
 //     emit a Base64 PDF document block for application/pdf FileParts on the
 //     Anthropic provider so user-uploaded PDFs actually reach Claude/Bedrock
 //     instead of being silently dropped.
-// See: https://github.com/coder/fantasy/commits/7d46e640327a
-replace charm.land/fantasy => github.com/coder/fantasy v0.0.0-20260602023814-7d46e640327a
+// 11) coder/fantasy#39, support Anthropic thinking_display natively.
+// See: https://github.com/coder/fantasy/commits/a2a3f2171ec8
+replace charm.land/fantasy => github.com/coder/fantasy v0.0.0-20260604204802-a2a3f2171ec8
 
 // coder/coder uses a fork of charmbracelet's fork of the Anthropic Go SDK
 // with performance improvements and Bedrock header cleanup.