refactor(catalog)!: split model catalog from pi-ai

Move bundled models, model cache/manager, thinking metadata, effort helpers,
provider descriptors/discovery, wire constants, and model identity utilities
into the new @oh-my-pi/pi-catalog package.

Update pi-ai to keep provider runtime/auth concerns, move catalog provider
metadata into CATALOG_PROVIDERS, and migrate coding-agent, agent, stats, docs,
and tests to import catalog values from pi-catalog.

Split coding-agent model registry helpers into discovery, roles, and models
config modules while preserving registry orchestration.

BREAKING CHANGE: @oh-my-pi/pi-ai no longer exports catalog subpaths such as
/models, /model-cache, /model-manager, /model-thinking, /effort,
/provider-models*, discovery helpers, and provider wire constants; use the
matching @oh-my-pi/pi-catalog subpaths instead.

packages/coding-agent/test/commit-model-selection-role-thinking.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it } from "bun:test";
-import { Effort, getBundledModel } from "@oh-my-pi/pi-ai";
+import { Effort } from "@oh-my-pi/pi-ai";
+import { getBundledModel } from "@oh-my-pi/pi-catalog/models";
 import { resolvePrimaryModel, resolveSmolModel } from "@oh-my-pi/pi-coding-agent/commit/model-selection";
 
 function getModelOrThrow(id: string) {