Enable deterministic builds (Deterministic=true)

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Problem

DBTools/DBTools.csproj sets <Deterministic>false</Deterministic>, which produces non-reproducible builds. Identical source can yield different assembly hashes across builds.

Proposed solution

1. Set <Deterministic>true</Deterministic> in DBTools.csproj
2. Verify build output is stable across repeated builds
3. If AssemblyInfo.cs embeds non-deterministic values (e.g. timestamps), remove or pin them

Acceptance criteria

• Deterministic is true in library csproj
• dotnet build succeeds with no warnings
• Repeated builds produce identical outputs (or document any intentional exceptions)

Context

Small, low-risk change suitable for a first contribution.