Adds AgentNetwork.Zone to the management config and passes it to the
agent-network manager, alongside the existing plumbing in the combined
binary. Nothing reads it yet -- the allocator that stamps it onto new rows
comes next -- so this commit is inert on its own.
## Describe your changes
Agent Network gates providers, policies, guardrails, budgets, usage,
access logs, and settings behind the single `agent_network` permission
module, so access is all-or-nothing: a future delegated role cannot be
scoped to a subset of the area (for example usage-only visibility).
This introduces dotted submodules (`agent_network.providers`,
`.policies`, `.guardrails`, `.budgets`, `.usage`, `.logs`, `.settings`)
and resolves grants with a cascade: exact module first, then its parent,
then the role's `AutoAllowNew` default. The agent network manager now
validates each operation against its matching submodule. `usage`
(aggregated counters, overview) is deliberately separate from `logs`
(request-level entries, which can contain captured prompts).
No role definitions change. No built-in role carries an explicit
`agent_network` entry, so every role resolves the submodules exactly as
it resolved the parent module before — pinned by a test that compares
each built-in role's answer on every submodule against its answer on
`agent_network`. Role additions that use these submodules come
separately.
