refactor: finish companion rename migration

Complete the remaining pi-to-companion rename across companion-os, web, vm-orchestrator, docker, and archived fixtures.

Verification:
- semantic rg sweeps for Pi/piConfig/getPi/.pi runtime references
- npm run check in apps/companion-os (fails in this worktree: biome not found)

Co-authored-by: Codex <noreply@openai.com>

packages/coding-agent/test/agent-session-dynamic-tools.test.ts

@@ -1,7 +1,7 @@
 import { existsSync, mkdirSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
-import { getModel } from "@mariozechner/pi-ai";
+import { getModel } from "@mariozechner/companion-ai";
 import { Type } from "@sinclair/typebox";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import { DefaultResourceLoader } from "../src/core/resource-loader.js";
@@ -16,7 +16,7 @@ describe("AgentSession dynamic tool registration", () => {
   beforeEach(() => {
     tempDir = join(
       tmpdir(),
-      `pi-dynamic-tool-test-${Date.now()}-${Math.random().toString(36).slice(2)}`,
+      `companion-dynamic-tool-test-${Date.now()}-${Math.random().toString(36).slice(2)}`,
     );
     agentDir = join(tempDir, "agent");
     mkdirSync(agentDir, { recursive: true });
@@ -37,9 +37,9 @@ describe("AgentSession dynamic tool registration", () => {
       agentDir,
       settingsManager,
       extensionFactories: [
-        (pi) => {
-          pi.on("session_start", () => {
-            pi.registerTool({
+        (companion) => {
+          companion.on("session_start", () => {
+            companion.registerTool({
               name: "dynamic_tool",
               label: "Dynamic Tool",
               description: "Tool registered from session_start",