Avoid repeated preindexed source refreshes

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• Use the freshest available source metadata or index.db timestamp when deciding whether a preindexed cache is stale.
• Align the default preindexed auto-update interval with winget-cli: 15 minutes.
• Add C# and Rust regression coverage for stale source metadata with a fresh local index.
• Clean up Rust temporary index files when replacement fails.
• Bump Pinget version surfaces to 0.8.2 via scripts\Set-PingetVersion.ps1 0.8.2.

WinGet comparison

WinGet checks source freshness before opening sources. For preindexed sources, it refreshes when there is no usable cached source package, or when the later of the cached source package version timestamp and source metadata LastUpdateTime is older than source.autoUpdateIntervalInMinutes. The default for that setting is 15 minutes; 0 disables auto-update. It also honors DoNotUpdateBefore to avoid retrying too soon after service throttling.

Pinget now mirrors the same practical behavior for its direct index.db cache: it refreshes when index.db is missing, or when the freshest available timestamp (LastUpdate metadata or index.db mtime) is older than the configured interval. Explicit source updates and explicit missing-version recovery can still force a refresh.

Benchmark

Final isolated pinget show Microsoft.PowerToys Release timing:

CLI	Cold run	Warm avg	Warm cache changes
C#	1690.3 ms	534.1 ms	0
Rust	1725.2 ms	348.8 ms	0

Validation

• dotnet test dotnet\src\Devolutions.Pinget.Core.Tests\Devolutions.Pinget.Core.Tests.csproj -c Release --nologo
• cargo test -p pinget-core --manifest-path rust\Cargo.toml
• cargo clippy -q --manifest-path rust\Cargo.toml --workspace --tests -- -D warnings
• cargo build -p pinget-cli --manifest-path rust\Cargo.toml --release
• dotnet test dotnet\src\Devolutions.Pinget.Core.Tests\Devolutions.Pinget.Core.Tests.csproj -c Release --filter "FullyQualifiedName~Show_PreindexedFreshIndexMtime|FullyQualifiedName~Show_PreindexedStaleIndex|FullyQualifiedName~Show_PreindexedExplicitMissingVersion|FullyQualifiedName~Show_PreindexedStaleIndex_WhenRefreshFails" --nologo
• cargo test -p pinget-core --manifest-path rust\Cargo.toml preindexed_
• cargo test -p pinget-core --manifest-path rust\Cargo.toml repository_options_capture_custom_host_settings
• dotnet build dotnet\Devolutions.Pinget.slnx -c Release --nologo
• cargo build -p pinget-cli --manifest-path rust\Cargo.toml
• cargo build -p pinget-com --manifest-path rust\Cargo.toml