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-grind/README.md

@@ -1,45 +0,0 @@
-# pi-grind
-
-Explicit grind mode for Pi.
-
-Features:
-
-- Auto-activates only when the user uses explicit grind cues in a prompt
-- Persists run state in session custom entries
-- Continues work on a heartbeat while running in `pi daemon`
-- Pauses automatically when the user sends a normal prompt
-
-Example prompts:
-
-- `Keep going on this until 5pm`
-- `Don't stop until the refactor is done`
-
-Commands:
-
-- `/grind start --until "5pm" Ship the refactor`
-- `/grind status`
-- `/grind pause`
-- `/grind resume`
-- `/grind stop`
-
-Settings:
-
-```json
-{
-  "pi-grind": {
-    "enabled": true,
-    "pollIntervalMs": 30000,
-    "cueMode": "explicit-only",
-    "requireDaemon": true,
-    "userIntervention": "pause",
-    "cuePatterns": [
-      "don't stop",
-      "keep going",
-      "keep running",
-      "run until",
-      "until done",
-      "stay on this until"
-    ]
-  }
-}
-```