refactor: migration to cpm

[Jaxelr]

Description

This PR moves our dependencies into centralized package management.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings

[Copilot]

Pull Request Overview

This PR centralizes package version management and standardizes target frameworks for all benchmark projects.

• Introduce Directory.Packages.props to manage package versions centrally
• Remove per-project version attributes and rely on central versions
• Add Directory.Build.props under benchmarks/ to unify TargetFramework and LangVersion

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
benchmarks/Insight.Database.Benchmarks/Insight.Database.Benchmarks.csproj	Removed explicit versions and moved TFM to Directory.Build.props
benchmarks/Insight.Database.Benchmarks.Sqlite/Insight.Database.Benchmarks.Sqlite.csproj	Removed explicit version and TFM
benchmarks/Insight.Database.Benchmarks.SqlServer/Insight.Database.Benchmarks.SqlServer.csproj	Removed TFM
benchmarks/Insight.Database.Benchmarks.Postgres/Insight.Database.Benchmarks.Postgres.csproj	Removed explicit version and TFM
benchmarks/Insight.Database.Benchmarks.MySql/Insight.Database.Benchmarks.MySql.csproj	Removed explicit version and TFM
benchmarks/Insight.Database.Benchmarks.Models/Insight.Database.Benchmarks.Models.csproj	Removed explicit versions and TFM
benchmarks/Directory.Build.props	Added shared TargetFramework and LangVersion
Insight.Database.Benchmarks.sln	Added Directory.Packages.props to solution items
Directory.Packages.props	New central package version file

Comments suppressed due to low confidence (1)

benchmarks/Insight.Database.Benchmarks/Insight.Database.Benchmarks.csproj:3

• [nitpick] This project no longer explicitly sets a TargetFramework (it was previously netstandard2.0) and now inherits net9.0 from Directory.Build.props. Please confirm this change is intentional or add an override if a different framework is required.

  <ItemGroup>