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/pi-channels/package.json

@@ -1,40 +0,0 @@
-{
-  "name": "@e9n/pi-channels",
-  "version": "0.1.0",
-  "description": "Two-way channel extension for pi — route messages between agents and Telegram, webhooks, and custom adapters",
-  "type": "module",
-  "keywords": [
-    "pi-package"
-  ],
-  "license": "MIT",
-  "author": "Espen Nilsen <hi@e9n.dev>",
-  "pi": {
-    "extensions": [
-      "./src/index.ts"
-    ]
-  },
-  "devDependencies": {
-    "@types/node": "^22.0.0",
-    "typescript": "^5.0.0"
-  },
-  "peerDependencies": {
-    "@mariozechner/pi-ai": "*",
-    "@mariozechner/pi-coding-agent": "*",
-    "@sinclair/typebox": "*"
-  },
-  "dependencies": {
-    "@slack/socket-mode": "^2.0.5",
-    "@slack/web-api": "^7.14.1"
-  },
-  "files": [
-    "CHANGELOG.md",
-    "README.md",
-    "package.json",
-    "src"
-  ],
-  "repository": {
-    "type": "git",
-    "url": "git+https://github.com/espennilsen/pi.git",
-    "directory": "extensions/pi-channels"
-  }
-}