Fix stale preindexed package details

[Marc-André Moreau (mamoreau-devolutions)]

Summary

Fixes stale WinGet package details for explicit version/channel requests in both the C# and Rust implementations.

• Stops explicit version requests from silently falling back to the latest available manifest when the requested version is missing.
• Adds bounded pre-indexed source refresh/retry behavior for explicit version misses so stale local indexes can recover once, then fail clearly if the version is still unavailable.
• Adds pre-indexed freshness policy support for existing indexes, with stale-cache fallback for non-explicit/latest requests when refresh fails.
• Preserves latest-version behavior when no explicit version/channel is requested.
• Prevents repeated source downloads for a single explicit request after a fresh stale-index refresh already ran.
• Replaces pre-indexed index.db through a temporary file in both implementations to avoid partially written active indexes.
• Handles V2 pre-indexed channel requests explicitly instead of ignoring unavailable channel metadata.

C# changes

• Added RepositoryOptions.PreIndexedSourceAutoUpdateInterval and MissingPackageVersionException.
• Updated V1, V2, and REST version selection to require exact explicit version/channel matches.
• Added pre-indexed TTL refresh, refresh attempt tracking, per-source refresh locking, diagnostics, and refresh-on-explicit-miss retry.
• Uses read-only SQLite with Pooling=False for pre-indexed reads so refresh replacement is safe on Windows.
• Added tests for strict version selection, REST misses, stale index refresh, stale fallback, refresh failure recovery, no double-refresh, and V2 channel rejection.

Rust changes

• Added RepositoryOptions.pre_indexed_source_auto_update_interval with builder support.
• Added strict V1/V2/REST version selection and a focused missing-version error.
• Added pre-indexed TTL refresh, bounded explicit-miss refresh/retry, recent refresh throttling, per-source refresh locks, and safe temp-file index replacement.
• Added an in-process fake pre-indexed source regression harness covering cache/indexing behavior end-to-end.
• Added tests for explicit miss refresh, still-missing failures, TTL refresh, stale fallback, no double-refresh, and exact/channel selectors.

Validation

• dotnet format dotnet\Devolutions.Pinget.slnx --verbosity minimal
• dotnet test dotnet\src\Devolutions.Pinget.Core.Tests\Devolutions.Pinget.Core.Tests.csproj -c Release --no-restore — 180 total, 179 passed, 1 skipped
• dotnet build dotnet\Devolutions.Pinget.slnx -c Release --no-restore
• pwsh -NoLogo -NoProfile -File (Resolve-Path 'dotnet\tests\RunTests.ps1') — 13 passed
• cargo +nightly fmt --manifest-path rust\Cargo.toml --all
• cargo clippy -q --manifest-path rust\Cargo.toml --workspace --tests -- -D warnings
• cargo test -p pinget-core --manifest-path rust\Cargo.toml — 151 passed
• cargo test -p pinget-cli --manifest-path rust\Cargo.toml — 9 passed
• cargo build -p pinget-cli --manifest-path rust\Cargo.toml
• git --no-pager diff --check