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/sdk-skills.test.ts

@@ -14,12 +14,12 @@ describe("createAgentSession skills option", () => {
   beforeEach(() => {
     tempDir = join(
       tmpdir(),
-      `pi-sdk-test-${Date.now()}-${Math.random().toString(36).slice(2)}`,
+      `companion-sdk-test-${Date.now()}-${Math.random().toString(36).slice(2)}`,
     );
     skillsDir = join(tempDir, "skills", "test-skill");
     mkdirSync(skillsDir, { recursive: true });
 
-    // Create a test skill in the pi skills directory
+    // Create a test skill in the companion skills directory
     writeFileSync(
       join(skillsDir, "SKILL.md"),
       `---