feat(x): thread the models.dev reasoning flag to the renderer

Widens the models.dev schema to keep the per-model `reasoning` boolean
and carries it through normalizeModels → ProviderSummary → models:list,
so the composer can gate the reasoning-effort control on actual model
capability. Gateway model lists (bare "vendor/model" ids from the
server) are annotated from the models.dev cache in one batched,
cache-only read; unknown models keep the flag absent, which the UI
treats as "hide the control".

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/x/packages/shared/src/ipc.ts

@@ -586,6 +586,9 @@ const ipcSchemas = {
           id: z.string(),
           name: z.string().optional(),
           release_date: z.string().optional(),
+          // models.dev "supports reasoning/extended thinking" flag; absent =
+          // unknown. Gates the composer's reasoning-effort control.
+          reasoning: z.boolean().optional(),
         })),
       })),
       lastUpdated: z.string().optional(),