feat(adagents): directory inverse-lookup + divergence detector (Parts 2+3 of #749)

Squashed onto main to resolve conflicts with #753 (publisher_domains compact
form, revoked_publisher_domains) and main HEAD. Final state of this PR:

- fetch_agent_authorizations_from_directory: async wrapper for GET /v1/agents/
  {agent_url}/publishers (per adcp#4823 / adcp#4828). Returns AgentDirectoryLookup
  with spec-conformant envelope (agent_url, directory_indexed_at, publishers,
  next_cursor). Accepts include=["properties"] to request per-publisher
  property_ids[] (per adcp#4894).
- detect_publisher_properties_divergence: full (publisher_domain, property_id)
  set-diff when directory returns property_ids[]; falls back to count-only
  comparison against directories that haven't deployed adcp#4894 yet.
  max_concurrency=20 default semaphore caps concurrent fetches at managed-
  network scale. sample_size=200 default opt-in for full sweep.
- AgentPublisherEntry / AgentDirectoryLookup / PublisherDivergence /
  DivergenceReport dataclasses; DiscoveryMethod / PublisherStatus Literal enums.
- AAO_PUBLISHER_DIRECTORY_URL env var supported (matches salesagent convention).
- Tests use respx.mock against spec-shaped JSON payloads.

Closes #749 Parts 2 and 3. Companion to #750 (Part 1: inline-resolution).

Author: bokelley

src/adcp/__init__.py

@@ -16,13 +16,20 @@
     AdagentsFetchResult,
     AdagentsValidationReport,
     AdAgentsValidationResult,
+    AgentDirectoryLookup,
+    AgentPublisherEntry,
     AuthorizationContext,
     DiscoveryMethod,
+    DivergenceReport,
     EntryErrorKind,
+    PublisherDivergence,
+    PublisherStatus,
+    detect_publisher_properties_divergence,
     domain_matches,
     fetch_adagents,
     fetch_adagents_with_cache,
     fetch_agent_authorizations,
+    fetch_agent_authorizations_from_directory,
     filter_revoked_selectors,
     get_all_properties,
     get_all_tags,
@@ -821,13 +828,20 @@ def get_adcp_version() -> str:
     "AdagentsEntryError",
     "AdagentsFetchResult",
     "AdagentsValidationReport",
+    "AgentDirectoryLookup",
+    "AgentPublisherEntry",
     "AuthorizationContext",
+    "detect_publisher_properties_divergence",
     "DiscoveryMethod",
+    "DivergenceReport",
     "EntryErrorKind",
     "fetch_adagents",
     "fetch_adagents_with_cache",
     "fetch_agent_authorizations",
+    "fetch_agent_authorizations_from_directory",
     "filter_revoked_selectors",
+    "PublisherDivergence",
+    "PublisherStatus",
     "validate_adagents_domain",
     "validate_adagents_structure",
     "verify_agent_authorization",