feat(journaling): support composition on plain grains

[ReubenBond]

Enables journaled state composition on ordinary grains and application-defined grain base classes. The standard state manager enrolls itself in the activation lifecycle in its grain-bound constructor, so injected durable state recovers during SetupState before OnActivateAsync and requests. AddJournalStorage supplies the scoped manager through a construction-only factory. Resolving journal state or a manager creates the activation's manager; configured features can materialize their state through shared activation setup.

This supersedes this PR's original IJournaledGrainParticipant.Initialize() proposal with the runtime's IConfigureGrainTypeComponents and GrainTypeSharedContext.AddActivationSetup composition boundary. A configurator selects grain classes once per type and registers a shared action which resolves activation-scoped feature services after grain construction and assignment, before lifecycle startup. Scoped features can enroll their existing lifecycle participants for asynchronous startup and shutdown.

DurableGrain remains an optional convenience for StateManager, GetOrCreateState, and WriteStateAsync. Grain code relies on lifecycle enrollment being complete when its scoped manager resolves. The standard manager establishes that guarantee in its grain-bound constructor; custom managers establish it in their constructor or registration factory. An enrollment failure disposes the partially constructed manager and propagates the original error. Explicit-JournalId and storage-only construction retain caller-owned initialization/disposal and independent journal identity.

The change includes focused composition, isolation, recovery, failure, constructor-enrollment, and provider-coherence coverage, along with updated Journaling guidance and source-backed compiled examples. README, documentation, and runnable Azure sample operations accept cancellation tokens and flow them through grain calls, journal writes, and provider I/O. Runnable clients use the host stopping token for operations and the configured shutdown deadline for graceful cleanup. The generated Journaling API matches the runtime foundation's surface after removing the unmerged participant addition; the released compatibility baseline is preserved.

Runtime prerequisite #11305 merged into dotnet/orleans:main at 9303d4ec7cd76ba7f9f41f61fc13774e86430003. This PR is rebased onto that upstream commit, so its diff contains only the Journaling composition changes. Review the immutable Journaling-only comparison.

Downstream consumers in #11280 and #10693 adapt separately: move feature materialization from the specialized participant bootstrap into shared activation setup, resolve state through context.ActivationServices, and enroll feature lifecycle work before startup. Their branches remain separately owned.

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Copilot review overview

🔵 Needs a closer look

Prevent stale work-item coalescing after recovery-generation changes and correct the related reset wording.

Review effort: Lite
Findings: None

What changed in this PR

Adds grain-scoped Journaling participants, initializing durable state before recovery.

Changes:

• Adds the participant contract and DurableGrain integration.
• Updates recovery-generation fencing and state rebinding.
• Adds lifecycle, recovery, failure, and factory tests.
• Updates the generated API surface.

File	Summary
test/​Orleans.Journaling.Tests/​StateManagerTests.cs	Tests recovery fencing scenarios.
test/​Orleans.Journaling.Tests/​JournaledGrainParticipantTests.cs	Tests participant lifecycle and activation behavior.
src/​Orleans.Journaling/​JournaledStateManager.cs	Adds recovery-generation fencing and state rebinding.
src/​Orleans.Journaling/​IJournaledGrainParticipant.cs	Defines the participant contract.
src/​Orleans.Journaling/​DurableGrain.cs	Resolves and initializes participants during construction.
src/​api/​Orleans.Journaling/​Orleans.Journaling.cs	Updates the generated public API.

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[github-actions]

Code coverage

Metric	Pull request
Lines	82.29% (112,547 / 136,771)
Branches	71.58% (32,473 / 45,367)

Report-only conclusion: current-main baseline stale.

The newest successful coverage run tested 9222be9, not current main d515d75.

Coverage combines every CI test matrix job, including providers, CodeGen, .NET 8/10, Linux, Windows, and macOS, using canonical physical source and branch identities.

The comparison remains report-only while normal line and branch variance is calibrated.

Coverage details

• Pull request commit: a2ebe0d35c
• View the pull request test run and coverage artifacts
• View the trusted coverage reporting run

[Copilot]

Copilot review overview

🔵 Needs a closer look

The recovery and activation changes require final human review.

Review effort: Lite
Findings: None

[Copilot]

Copilot review overview

🔵 Needs a closer look

The explicit-JournalId test does not activate or initialize a journaling participant as intended.

Review effort: Lite
Findings: None

[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved blocking issues were identified.

Review effort: Lite
Findings: None

[Copilot]

Copilot review overview

🔵 Needs a closer look

A moderate concurrency issue in IGrainContextActivator must be addressed before approval.

Review effort: Lite
Findings: None

[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved blocking issues were identified.

Review effort: Lite
Findings: None

[Copilot]

Copilot review overview

🟢 Approval recommended

No blocking issues were identified, and the approval assessments support approval.

Review effort: Lite
Findings: None