Bun compiled binaries have an empty process.env when running inside
sandbox environments (e.g. nono on Linux/macOS). This broke API key
detection and model discovery because all process.env.* lookups returned
undefined.
- Add restoreSandboxEnv() helper that reads /proc/self/environ when Bun
is detected and process.env is empty, populating process.env before
any other code runs (coding-agent/src/bun/cli.ts entry point)
- Add getProcEnv() fallback in env-api-keys.ts for direct @mariozechner/pi-ai
consumers that may not go through the coding-agent entry point
- Add unit tests for restoreSandboxEnv