chore: point .env at 1Password Environment

[remote-llm]

TL;DR

This repo's .env now comes from a 1Password Environment instead of a file
pasted in by hand. This PR adds only the pointer — no secrets, no behaviour
change.

  1Password Environment                    this repo
  aperiodic-io/atlas
           ▲                               .env.1password
           └───────── named by ────────────┘   (committed)
           │
           ▼
     op-env run -- <cmd>     values injected at run time, nothing on disk

What it adds

File	1Password Environment
.env.1password	aperiodic-io/atlas

Naming follows <github-org>/<repo>[/<app>] [stage].

Using it

op-env check              # auth + which Environment + how many vars
op-env run -- <command>   # preferred: nothing written to disk
op-env write              # only when a tool insists on a real .env file

op-env walks up from $PWD to the nearest .env.1password, so each app
directory gets its own Environment.

Tooling and setup: https://github.com/szemyd/ssh-llm-setup

🤖 Generated with Claude Code