hives read the forge through their own swarm-minted read account

swarm-controller now gives every hive in its directory a forge account,
`hive-<hive>`, in a new `hives` team of `agent-configs` (read on
`repo.code` + `repo.pulls`, every repo including later ones), and mints
one `read:repository` token named `swarm-hive` into the store at
`swarm/hives/<hive>/forge/token`. A five-minute pass queues a
`MintHiveForgeToken` node for a hive whose token is missing or no longer
matches the forge, whose account is missing, or whose team membership or
team settings drifted. A hive whose store or forge read failed is never
queued, so an outage cannot rotate every hive's token. The token decision
reuses `agent_token`'s classifier and replace step, now parameterised by
name and scopes.

An agent may be called `hive-<x>`. The hive account is created with
`hive-<hive>@hives.hyperhive.local` and the job refuses an account by that
name with any other email before it locks it down, adds it to the team or
mints for it; agent creation already refuses the hive's account by the
same email check.

The controller's bao policy gains the `swarm/hives/+/forge/token` leaf
(create/read/update), pinned by the bao-grants module-eval assertion. The
hive's own policy already reads `swarm/hives/<hive>/*`.

hive-c0re reads that token through `forge::reader_token()`, falling back
to the core token file when the store holds none, and uses it for:
fetching a merged config rev (swarm deploy, `hivectl forge
reconcile-config`), reseeding a purged `applied`, the meta-update
cascade's fast-forward, seeding `proposed` on first deploy, and finding
the PR that merged a refused rev. Those reads no longer require a local
`hive-forge` container. The `/knowledge` clone moves from the forge
host's boot sweep into the knowledge pull, so every hive clones it.

Posting the deploy-failure comment on that PR stays on the core token.

Refs #4851

nix/host-modules/swarm-bao.nix

@@ -429,6 +429,10 @@ let
       capabilities = ["create", "read", "update"]
     }
 
+    path "${credentialMountPath}/data/swarm/hives/+/forge/token" {
+      capabilities = ["create", "read", "update"]
+    }
+
     path "${credentialMountPath}/data/${ciRunnerTokenLeaf}" {
       capabilities = ["create", "update"]
     }