feat(cmd): agent tokens and host-side proposals get admin commands

Two entry points were missing, and both left a deployment unable to do
the thing it exists for.

`token create|list|revoke` — db/ has had the whole agent-token lifecycle
since Phase 1, but nothing called it: no CLI, no page. A fresh instance
therefore had no credential for the agent write plane, which refuses an
anonymous caller by design, and the only way to mint one was an operator
hand-writing an INSERT with a sha256 hash. The plaintext is printed once
and never logged; only its hash is stored, and the listing deliberately
omits the hash so nobody mistakes it for the credential.

`doc propose ~owner/space <file>...` — the two agent write surfaces are
remote and so need a bearer token. When the operator and the documents
are already on the host, that token is ceremony: the process can open
Postgres and the bare repositories directly, so it constructs the agent
principal itself rather than resolving one from an agent_token row.
Provenance is not waived — --agent and --session are recorded exactly as
a remote agent's are, so `git log` cannot tell the two apart, and neither
can a reviewer. It calls service.Propose, so If-Match, the branch cut,
the trailers and the auto-merge gate stay spelled once.

Flags parse before, after and between the positionals: Go's flag package
stops at the first non-flag, which would make `doc propose ~bigbes/rfcs
spec.md --title x` drop --title and fail one layer down complaining
about a missing title rather than the flag it ignored.

spec-rsb, spec-ovo