fix(adagents): accept property-level publisher_domain in managerdomain scope gate

[bokelley]

The explicit-publisher-scoping gate from #4173 only inspected per-agent paths (`authorized_agents[].publisher_properties[].publisher_domain` and `authorized_agents[].collections[].publisher_domain`). Probing real production manifests after #4251 landed showed every managed-network manager rejects under that gate — Mediavine, the only manager currently serving an `adagents.json` against a publisher with a `MANAGERDOMAIN` pointer (`homestratosphere.com → mediavine.com`), uses property-level scoping with tag-based agent references:

```json
"properties": [{
"property_id": "the_hollywood_gossip",
"publisher_domain": "thehollywoodgossip.com",
"tags": ["scope3-aee"]
}],
"authorized_agents": [{
"authorization_type": "property_tags",
"property_tags": ["scope3-aee"]
}]
```

The cross-publisher commitment IS expressly declared — just routed through the property layer rather than re-spelled per-agent.

Fix

Gate now accepts either shape:

• Per-agent paths (unchanged): `publisher_properties[].publisher_domain` or `collections[].publisher_domain` directly names the publisher.
• Property-level paths (new): a `properties[]` entry carries `publisher_domain` matching the source AND at least one `authorized_agents[]` entry reaches that property indirectly via `property_ids` or `property_tags`.

Cross-publisher confusion still fails closed:

• A property belonging to a different publisher can't satisfy the gate.
• An agent referencing a tag none of the publisher's properties carry can't satisfy it either.

Tests

• `property_tags` + property-level `publisher_domain` (Mediavine pattern) — accepts.
• `property_ids` + property-level `publisher_domain` — accepts.
• Foreign-property cross-publisher rejection — fails closed.
• No-matching-tag rejection (publisher property has tags A, agent points at tag B) — fails closed.

84/84 unit tests green.

Discussion

Sent design question to @patmmccann on #4173 (comment) about whether per-agent should remain the only normative shape, or both are equally valid. Landing the additive fix in the meantime since:

1. The property-level shape is in deployed production manifests today (Mediavine).
2. The cross-publisher commitment invariant holds either way — manager must positively name the publisher somewhere in the manifest.
3. Without this, the entire managerdomain fallback feature is effectively dormant against real ecosystems.

Will update if Patrick prefers a stricter reading.

Refs #4173, #4200, #4251.