## What this fixes
Adds `discord.py`, `python-telegram-bot`, `slack-bolt`, and other messaging platform libraries to the default Hermes derivation. Also adds a `docker-image` OCI image target for k3s deployment.
Fixes https://os.scoble.me/forgejo/sscoble/hermes-speckl/issues/2
## Problem
The `[all]` extras group in upstream hermes-agent (NousResearch) stopped including the `messaging` dependency group on 2026-05-12 — it switched to lazy-install at runtime. But our Nix-built container images running on k3s have no `pip` available, so lazy installation fails.
Agent logs show:
```
WARNING gateway.run: Discord: discord.py not installed
WARNING gateway.run: No adapter available for discord
```
## Changes
- Added `extraDependencyGroups = ["messaging"]` override on the hermes-agent derivation
- Added `docker-image` OCI image target built with `dockerTools.buildLayeredImage`
- Fixed scoping: `forAllSystems` moved into `let...in` binding for flake-parts compatibility
- Added `flake.lock` (previously missing)
## After Merge
1. Build the OCI image:
```
nix build .#docker-image
```
2. Import into containerd:
```
sudo ctr -n k8s.io images import result
sudo ctr -n k8s.io images tag --force hermes-speckl/sme:latest docker.io/hermes-speckl/sme:latest
```
3. Restart the demo concierge:
```
kubectl delete pod -n cust-demo -l agent=concierge
```
4. Verify:
```
kubectl logs -n cust-demo -l agent=concierge --tail=5
# Should show Discord connected, not "discord.py not installed"
```
**Verified:** The image builds successfully and includes `discord.py==2.7.1`, `python-telegram-bot==22.6`, and `slack-bolt==1.27.0`. Image imported to containerd and ready for deployment.
Reviewed-on: https://os.scoble.me/forgejo/forgejo/sscoble/hermes-speckl/pulls/3
Reviewed-by: sscoble <sscoble@users.noreply.git>
Co-authored-by: agent-engineering <engineering@marcus.local>
Co-committed-by: agent-engineering <engineering@marcus.local>
