refactor(packages/coding-agent): migrated imports to pi-ai submodules

- Migrated Effort and THINKING_EFFORTS imports to @oh-my-pi/pi-ai/effort in CLI args and launch command files.
- Split model-registry dependencies across focused @oh-my-pi/pi-ai submodules instead of the root barrel export.

packages/coding-agent/src/cli/args.ts

@@ -1,7 +1,7 @@
 /**
  * CLI argument parsing and help display
  */
-import { type Effort, THINKING_EFFORTS } from "@oh-my-pi/pi-ai";
+import { type Effort, THINKING_EFFORTS } from "@oh-my-pi/pi-ai/effort";
 import { APP_NAME, CONFIG_DIR_NAME, logger } from "@oh-my-pi/pi-utils";
 import chalk from "chalk";
 import { parseEffort } from "../thinking";