Add Apex Fortunes benchmarks

[sebastienros]

Apex.PgClient now provides a pipelined PostgreSQL path worth measuring alongside the existing TechEmpower Fortunes implementations. This adds source-built benchmark scenarios for both a dedicated high-performance application and an opt-in Minimal API route without replacing the existing Npgsql/Dapper baseline.

Summary

• Add a dedicated Platform-style Apex Fortunes app using a pool-wide prepared statement, borrowed UTF-8 row memory, and RazorSlices rendering.
• Add /fortunes/apex to the Minimal app while preserving /fortunes and the existing Npgsql/Dapper endpoints.
• Centrally reference Apex.PgClient 0.1.0-preview.3 and target .NET 10 where required.
• Add standard source-based Crank scenarios with PostgreSQL, 56 Apex connections, pipeline depths 64 and 16, and 1024 HTTP load connections.
• Add regular database trend runs named FortunesPlatformApex and FortunesMinimalApisApex, each explicitly using 1024 HTTP connections.

Validation

• Both projects build in Release against the published Apex package API.
• Benchmark and pipeline YAML plus project XML parse successfully.
• The branch contains no local project references, machine-specific profiles, prepublished artifacts, or PlatformBenchmarks source changes.