Refactor GAgent registry ownership ports

[louis4li]

Summary

Refactors the legacy IGAgentActorStore surface into explicit GAgent registry command, query, and command-admission ports for issue #348.

What Changed

• Adds IGAgentActorRegistryCommandPort, IGAgentActorRegistryQueryPort, and IScopeResourceAdmissionPort contracts.
• Replaces the actor-backed store implementation with ActorBackedGAgentRegistryPorts backed by GAgentRegistryGAgent.
• Adds typed registry admission messages and GAgentRegistryOperation enum.
• Moves list paths to eventually consistent registry read-model snapshots with StateVersion, UpdatedAt, and ObservedAt freshness fields.
• Moves NyxID chat, StreamingProxy, and draft-run target operations to registry admission instead of projection/list-based ownership checks.
• Enforces create-before-register semantics for immediately operable resources and adds rollback for registration failure/cancellation paths.
• Disables direct generic POST /{scopeId}/gagent-actors registration with a 405 response so target creation stays in capability command endpoints.
• Adds docs/canon/gagent-registry-ownership.md and updates related lifecycle docs.
• Adds architecture guard coverage to prevent production references to the retired IGAgentActorStore/ActorBackedGAgentActorStore abstractions.

Impact

This separates registry lifecycle writes, list queries, and command-path admission into distinct semantics. Command admission no longer depends on projection freshness, while list responses remain explicitly eventually consistent.

Validation

Passed:

• git diff --check
• bash tools/ci/test_stability_guards.sh
• dotnet test test/Aevatar.GAgentService.Tests/Aevatar.GAgentService.Tests.csproj --no-restore --nologo --filter "FullyQualifiedName~GAgentDraftRunActorPreparationServiceTests"
• dotnet test test/Aevatar.AI.Tests/Aevatar.AI.Tests.csproj --no-restore --nologo --filter "FullyQualifiedName~StreamingProxyEndpointsCoverageTests"
• dotnet test test/Aevatar.GAgentService.Integration.Tests/Aevatar.GAgentService.Integration.Tests.csproj --no-restore --nologo --filter "FullyQualifiedName~ScopeGAgentEndpointsTests"

Known existing blocker observed while reviewing:

• bash tools/ci/architecture_guards.sh reaches playground_asset_drift_guard and fails because demos/Aevatar.Demos.Workflow.Web/wwwroot/app.js differs from a freshly built CLI playground asset. This appears unrelated to the registry ownership change but still blocks the full guard command until asset drift is reconciled.

[codecov]

Codecov Report

❌ Patch coverage is 79.20489% with 68 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.59%. Comparing base (298cec8) to head (f84ca16).
⚠️ Report is 7 commits behind head on dev.

Files with missing lines	Patch %	Lines
...ture/ActorBacked/ActorBackedGAgentRegistryPorts.cs	74.25%	31 Missing and 12 partials ⚠️
...tService.Hosting/Endpoints/ScopeGAgentEndpoints.cs	76.00%	16 Missing and 2 partials ⚠️
...peGAgents/GAgentDraftRunActorPreparationService.cs	92.30%	1 Missing and 3 partials ⚠️
...e.Abstractions/ScopeGAgents/GAgentRegistryPorts.cs	89.65%	3 Missing ⚠️

@@            Coverage Diff             @@
##              dev     #452      +/-   ##
==========================================
- Coverage   70.59%   70.59%   -0.01%     
==========================================
  Files        1208     1208              
  Lines       86806    87013     +207     
  Branches    11369    11383      +14     
==========================================
+ Hits        61284    61424     +140     
- Misses      21093    21146      +53     
- Partials     4429     4443      +14     

Flag	Coverage Δ
ci	70.59% <79.20%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...oProjectionReadModelServiceCollectionExtensions.cs	91.53% <ø> (ø)
...DependencyInjection/ServiceCollectionExtensions.cs	100.00% <100.00%> (ø)
...e.Abstractions/ScopeGAgents/GAgentRegistryPorts.cs	89.65% <89.65%> (ø)
...peGAgents/GAgentDraftRunActorPreparationService.cs	88.67% <92.30%> (+5.34%)	⬆️
...tService.Hosting/Endpoints/ScopeGAgentEndpoints.cs	83.29% <76.00%> (-3.18%)	⬇️
...ture/ActorBacked/ActorBackedGAgentRegistryPorts.cs	74.25% <74.25%> (ø)

... and 3 files with indirect coverage changes

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[louis4li]

补充说明一下这轮 review 的处理边界：

• 前三项属于仍然存在、但不在这次 registry ports/dev diff 修复范围内的 ownership/admission 架构债务，已单独开 issue 跟踪：Track remaining ownership/admission paths that still depend on read models or actor ID shape #462。

  • StudioMemberService.BindAsync 仍依赖 StudioMember projection readmodel 做 bind admission。
  • relay scope fallback 仍通过 ChannelBot registration projection 按 API key 反查 scope。
  • scoped relay conversation actorId 仍编码 scope ownership 信息。

• 后两项已在本 PR 内修复：

  • registry register receipt 不再把普通 dispatch ACK 直接声明为 AdmissionVisible；现在会显式验证 admission visibility，验证不到时降级为 AcceptedForDispatch。
  • unregister receipt 不再返回 AdmissionVisible，新增并返回 AdmissionRemoved，IsAdmissionVisible 对该阶段为 false。

同时补了 NyxID create conversation 的回滚逻辑：当注册没有达到 admission-visible 时，会 unregister registry entry 并 destroy actor，避免返回成功但留下半成品 actor/ownership 状态。