fix(fireworks): route Fireworks models through resolveModel everywhere

pi-ai's getModel/getModels does not know about the Fireworks providers
(fireworks, fireworks-firepass); both live under our local model-resolver
because Fireworks speaks the Anthropic-compat endpoint with Bearer auth
at https://api.fireworks.ai/inference, not pi-ai's built-in catalog.

Three call sites were still hitting pi-ai directly and failing silently
for Fireworks:

1. connector-model-policy.ts — listProviderModels() caught the pi-ai
   throw and returned []. The "Fire Pass (CEO runtime)" card in the
   Team Models onboarding step therefore showed "暂无模型 / 已启用 0/0",
   blocking users on Fire Pass from continuing onboarding.

2. worker/worker-runner.ts — getModel() threw mid-run when the selected
   connector was Fireworks, so the worker could never actually execute
   an agent turn against Fire Pass or the curated Fireworks model set.
   Now uses resolveModel() + the Fireworks-specific Bearer header from
   resolveExtraStreamHeaders() so streamSimple hits the correct endpoint
   with the correct auth.

3. agent-runtime/cost-writer.ts — cost observation silently wrote
   amount_usd=null for Fireworks runs because getModel() threw inside
   the try/catch. Now resolves via resolveModel() so the Fireworks
   curated contextWindow/maxTokens are visible to calculateCost().

Verification: pnpm typecheck 0 / pnpm lint 0-0 / pnpm build:verify 0-0
/ pnpm test:unit 508/508.

src/main/agent-runtime/cost-writer.ts

@@ -1,6 +1,7 @@
-import { calculateCost, getModel, type Usage } from "@mariozechner/pi-ai";
+import { calculateCost, type Usage } from "@mariozechner/pi-ai";
 import type { AppDatabase } from "@main/database";
 import { getConnectorDefinition } from "@main/connectors";
+import { resolveModel } from "@main/model-resolver";
 
 export interface CostWriterDeps {
   db: AppDatabase;
@@ -29,7 +30,7 @@ export class CostWriter {
     try {
       const definition = getConnectorDefinition(input.connectorId);
       if (definition.provider) {
-        const model = getModel(definition.provider as never, input.modelId as never);
+        const model = resolveModel(definition.provider, input.modelId);
         if (model) {
           const cost = calculateCost(model, input.usage);
           amountUsd = Number.isFinite(cost.total) ? cost.total : null;