deploy: give every option an enable, and name the controller one

Two corrections from review, applied forward on this branch rather than
by rewriting it.

`deploy.<service>` was a bare bool, which makes
`deploy.forgejo = { enable; ci; }` unrepresentable -- the nested
CI-runner sub-option this namespace was designed around. Every entry is
now an attrset with an `enable`, so a second per-host deployment
decision becomes an ordinary addition rather than a migration.

`deploy.controller` is now `deploy.swarm-controller`, consistent with
`deploy.swarm-ui`, which was introduced in the same commit.

89 references rewritten across 24 files -- nix, Rust, docs, and the
repo's own CLAUDE.md.

The prefix-anchored sweep missed exactly one, and it was live code:
hive-tls.nix spells it `hyperhiveCfg.deploy.controller` -- the only
`hyperhiveCfg` prefix among 45 references. A suffix grep
(`\.deploy\.<name>`) finds it; a path-anchored one cannot, because the
head of a reference is whatever alias the reading file happens to bind.

docs/persistence.md

@@ -472,7 +472,7 @@ snapshot contains and how the store authenticates a sender.
 ## `/var/lib/swarm-controller/` (swarm-controller host only)
 
 Only present on the one host running
-`services.hyperhive.deploy.controller`. systemd `StateDirectory=`,
+`services.hyperhive.deploy.swarm-controller.enable`. systemd `StateDirectory=`,
 so it survives restarts and redeploys.
 
 - `webhook-secret` — the HMAC key the swarm's forge webhooks are signed