refactor: switched to upstream @mariozechner/pi-ai and removed unused packages

- Replaced local @oh-my-pi/pi-ai with upstream @mariozechner/pi-ai@0.37.4
- Added sessionId support to agent for provider caching (OpenAI Codex)
- Deleted packages/ai (now using upstream)
- Deleted packages/mom (unused)
- Deleted packages/web-ui (unused)

packages/coding-agent/examples/custom-tools/README.md

@@ -63,7 +63,7 @@ See [docs/custom-tools.md](../../docs/custom-tools.md) for full documentation.
 
 ```typescript
 import { Type } from "@sinclair/typebox";
-import { StringEnum } from "@oh-my-pi/pi-ai";
+import { StringEnum } from "@mariozechner/pi-ai";
 import { Text } from "@oh-my-pi/pi-tui";
 import type { CustomToolFactory } from "@oh-my-pi/pi-coding-agent";
 
@@ -114,7 +114,7 @@ renderResult(result, { expanded, isPartial }, theme) {
 **Use StringEnum for string parameters** (required for Google API compatibility):
 
 ```typescript
-import { StringEnum } from "@oh-my-pi/pi-ai";
+import { StringEnum } from "@mariozechner/pi-ai";
 
 // Good
 action: StringEnum(["list", "add"] as const);

packages/coding-agent/examples/custom-tools/subagent/index.ts

@@ -15,8 +15,8 @@
 import * as fs from "node:fs";
 import * as os from "node:os";
 import * as path from "node:path";
+import type { Message } from "@mariozechner/pi-ai";
 import type { AgentToolResult } from "@oh-my-pi/pi-agent-core";
-import type { Message } from "@oh-my-pi/pi-ai";
 import type { CustomTool, CustomToolAPI, CustomToolFactory } from "@oh-my-pi/pi-coding-agent";
 import { type AgentConfig, type AgentScope, discoverAgents, formatAgentList } from "./agents";