Description
## Problem
Every container on a land needs to know the NATS URL to connect to the forest. Currently this is hardcoded per-container — either in config files (`nats.url: nats://nimsforest.nimsforest.com:4222`) or env vars (`NATS_URL=nats://...`). This is fragile and repetitive.
The land already knows its forest connection (configured in `/etc/land.yaml`). Its containers shouldn't need to be told separately.
## Proposal
Land should inject the NATS URL into all its containers automatically. Each container connects to its own land's forest, which in turn is clustered (via leaf nodes) with other lands in that organization.
The container doesn't need to know the global topology — it just talks to "my forest" and the forest handles routing across the organization's land cluster.
## Current state
- Land config (`/etc/land.yaml`) has `nats: nats://nimsforest.nimsforest.com:4222`
- Each container independently configures its own NATS URL (config file or env var)
- If the NATS URL changes, every container's config must be updated individually
- Some containers get it via env var, some via mounted config — no consistency
## Desired state
- Land injects `NATS_URL` env var into all containers automatically (from its own config)
- Containers that need NATS just read `NATS_URL` from env — no per-container config needed
- When a land's forest moves or the NATS URL changes, only land's config needs updating
- Containers are portable across lands without config changes
Nebula's reasoning: This is a solid infrastructure improvement that eliminates repetitive per-container NATS configuration and reduces the risk of config drift when URLs change. Not critical since everything works today, but medium priority because it directly reduces operational toil and makes containers portable across lands — a key enabler as the fleet grows. Title, description, category, and project are all well-defined already.