feat: drive reasoning variants from models.dev reasoning_options

Parse the curated reasoning_options field from models.dev api.json and use
its effort values to generate reasoning variants instead of the hardcoded
per-package tables, in both the v1 provider catalog and the v2 catalog plugin.

- core: ModelsDev.ReasoningOption discriminated union (toggle | effort |
  budget_tokens); effort values stay open strings and unknown option types
  are tolerated since api.json is cast, not decoded
- core: ReasoningVariants shared per-package effort encoder used by v1
  ProviderTransform.variants and the v2 ModelsDevPlugin
- core: v2 catalog generates effort variants from reasoning_options;
  curated experimental modes win id collisions; anthropic profile gains
  the effort semantic
- llm: anthropic protocol supports adaptive thinking, lowers effort to
  output_config.effort, and sends the effort-2025-11-24 beta header
- opencode: resolved Provider.Model carries capabilities.reasoningOptions
  (unknown types and null effort values dropped at the mapping boundary);
  config models accept reasoning_options; models without usable effort
  data fall back to the hardcoded tables unchanged

Catalog-wide audit vs live api.json: 2975 models byte-identical, 38 diffs,
all data correcting stale hardcoded effort lists.

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -1816,6 +1816,20 @@ export type ProviderConfig = {
       release_date?: string
       attachment?: boolean
       reasoning?: boolean
+      reasoning_options?: Array<
+        | {
+            type: "toggle"
+          }
+        | {
+            type: "effort"
+            values: Array<string>
+          }
+        | {
+            type: "budget_tokens"
+            min?: number
+            max?: number
+          }
+      >
       temperature?: boolean
       tool_call?: boolean
       interleaved?:
@@ -2082,6 +2096,20 @@ export type Model = {
   capabilities: {
     temperature: boolean
     reasoning: boolean
+    reasoningOptions?: Array<
+      | {
+          type: "toggle"
+        }
+      | {
+          type: "effort"
+          values: Array<string>
+        }
+      | {
+          type: "budget_tokens"
+          min?: number
+          max?: number
+        }
+    >
     attachment: boolean
     toolcall: boolean
     input: {