Add pluggable envelope ID generation with GuidV7 option

[jeremydmiller]

Summary

Fixes #2375

• Problem: NewId.NextSequentialGuid() generates envelope IDs based on machine identity (MAC/DNS hostname). In cloud environments where multiple instances share network properties (Google Cloud Run, Kubernetes, serverless), this produces duplicate envelope IDs causing Duplicate incoming envelope errors.
• Solution: New EnvelopeIdGeneration enum with NewId (default, backward compatible) and GuidV7 (Guid.CreateVersion7() per RFC 9562) options.
• Implementation: Static Func<Guid> delegate on Envelope set once at startup — zero runtime branching overhead. All internal NewId.NextSequentialGuid() calls replaced with Envelope.IdGenerator().

Usage

using var host = await Host.CreateDefaultBuilder()
    .UseWolverine(opts =>
    {
        // Recommended for greenfield apps and cloud deployments
        opts.EnvelopeIdGeneration = EnvelopeIdGeneration.GuidV7;
    }).StartAsync();

Files changed

File	Change
WolverineOptions.cs	Added EnvelopeIdGeneration enum and property
Envelope.cs	Added static IdGenerator delegate, property initializer uses it
WolverineRuntime.cs	Sets Envelope.IdGenerator at startup based on config
CloudEventsMapper.cs	Uses Envelope.IdGenerator()
DurableReceiver.cs	Uses Envelope.IdGenerator() (2 occurrences)
EnvelopeGenerator.cs	Uses Envelope.IdGenerator()
messages.md	Documentation with comparison table

Test plan

• 7 new tests pass (default setting, NewId sanity, V7 version bits, time ordering, cross-thread uniqueness, InvokeAsync integration, delegate wiring)
• CoreTests: 1221 passed, 0 failed

🤖 Generated with Claude Code