The internal forge is the canonical store for the meta flake, every
agent's config repo, and the internal/* repos, so it can no longer be
optional. Remove the services.hyperhive.forge.enable toggle:
- hive-forge.nix: drop the `enable` option; the forge config now
deploys gated on `services.hyperhive.enable` (it ships with hyperhive).
- hive-c0re.nix: HIVE_FORGE_URL env unconditional; forge-public-URL gate
drops the enable check (keeps behindGateway).
- hive-gateway.nix: local /etc/hosts forge entry keyed on behindGateway.
- hive-ci.nix: drop the now-moot `forge.ci.enable requires forge.enable`
assertion (forge is always present); reword the option doc.
- nix/docs/default.nix: drop the `forge.enable = mkForce false` stub
(option gone); the options-doc eval stays light via hyperhive.enable.
- hive-c0re forge.rs / hivectl.rs: reword 'forge.enable = true' error
text to 'wait for hive-c0re to start the container' (the runtime
token-absent path is unchanged — it's a bootstrap-timing check, not
the opt-out).
- docs/approvals.md, docs/ci.md: drop stale forge.enable references.
Migration: configs that set `services.hyperhive.forge.enable = false`
must drop the line — the forge is now mandatory.
Prereq/companion to #1838 (PR-based config flow, which assumes the forge
is always present).
2b4e928afe