Daemon: refuse leased requests that name no session at request admission #4171

Follow-up from #3931 and #4159.

#4159 makes the CLI refuse every command on a leased remote connection unless it names a session (--session, AGENT_DEVICE_SESSION or config). The rule is enforced in the CLI, though. A review of #4159 found that direct daemon RPC callers are not covered: a request with no session becomes default, then <tenant>:default (packages/daemon/src/server/http/http-rpc-methods.ts:48, packages/daemon/src/sessions/request-admission.ts:48). Against an isolated real daemon, an unnamed authenticated agent_device.lease.allocate allocated a proxy lease, and unnamed leased commands reached normal dispatch.

Required behavior

• Daemon request admission records whether the caller supplied a session before it defaults one.
• A request that would allocate, use or release a lease from a lease provider, with no caller-supplied session, is refused with the same typed reason (REMOTE_SESSION_REQUIRED) before allocation or dispatch.
• Requests with no lease provider are unchanged.
• Tests run against a real daemon: an unnamed lease.allocate is refused, an unnamed leased command is refused, and named requests are unaffected.