refactor(core): split index.ts and config-handler.ts into focused modules

Main entry point:
- create-hooks.ts, create-tools.ts, create-managers.ts
- plugin-interface.ts: plugin interface types
- plugin/ directory: plugin lifecycle modules

Config handler:
- agent-config-handler.ts, command-config-handler.ts
- tool-config-handler.ts, mcp-config-handler.ts
- provider-config-handler.ts, category-config-resolver.ts
- agent-priority-order.ts, prometheus-agent-config-builder.ts
- plugin-components-loader.ts

src/plugin-handlers/provider-config-handler.ts

@@ -0,0 +1,36 @@
+import type { ModelCacheState } from "../plugin-state";
+
+type ProviderConfig = {
+  options?: { headers?: Record<string, string> };
+  models?: Record<string, { limit?: { context?: number } }>;
+};
+
+export function applyProviderConfig(params: {
+  config: Record<string, unknown>;
+  modelCacheState: ModelCacheState;
+}): void {
+  const providers = params.config.provider as
+    | Record<string, ProviderConfig>
+    | undefined;
+
+  const anthropicBeta = providers?.anthropic?.options?.headers?.["anthropic-beta"];
+  params.modelCacheState.anthropicContext1MEnabled =
+    anthropicBeta?.includes("context-1m") ?? false;
+
+  if (!providers) return;
+
+  for (const [providerID, providerConfig] of Object.entries(providers)) {
+    const models = providerConfig?.models;
+    if (!models) continue;
+
+    for (const [modelID, modelConfig] of Object.entries(models)) {
+      const contextLimit = modelConfig?.limit?.context;
+      if (!contextLimit) continue;
+
+      params.modelCacheState.modelContextLimitsCache.set(
+        `${providerID}/${modelID}`,
+        contextLimit,
+      );
+    }
+  }
+}