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.

codersdk/chats.go

@@ -1229,6 +1229,7 @@ type ChatModelAnthropicProviderOptions struct {
 	SendReasoning          *bool                              `json:"send_reasoning,omitempty" description:"Whether to include reasoning content in the response"`
 	Thinking               *ChatModelAnthropicThinkingOptions `json:"thinking,omitempty" description:"Configuration for extended thinking"`
 	Effort                 *string                            `json:"effort,omitempty" label:"Reasoning Effort" description:"Controls the level of reasoning effort" enum:"low,medium,high,xhigh,max"`
+	ThinkingDisplay        *string                            `json:"thinking_display,omitempty" label:"Thinking Display" description:"Controls how Anthropic returns thinking content" enum:"summarized,omitted"`
 	DisableParallelToolUse *bool                              `json:"disable_parallel_tool_use,omitempty" description:"Whether to disable parallel tool execution"`
 	WebSearchEnabled       *bool                              `json:"web_search_enabled,omitempty" description:"Enable Anthropic web search tool for grounding responses with real-time information"`
 	AllowedDomains         []string                           `json:"allowed_domains,omitempty" label:"Web Search: Allowed Domains" description:"Restrict web search to these domains (cannot be used with blocked_domains)"`