Fix outdated command missing packages, improve output formatting

[Copilot]

The outdated command silently skipped packages due to several bugs in version resolution. Console and markdown table output had inconsistent formatting.

Bug fixes — missing packages

• Premature prerelease fallback in NuGetMetadataService: A goto retry inside the version iteration loop switched to prerelease mode the moment a single stable version failed the framework check, skipping all older compatible stable versions entirely. Removed the inner goto; the existing post-loop fallback handles this correctly.

• KeyNotFoundException in version lookup: Direct dictionary indexer on TargetFrameworkVersions threw when the exact NuGetFramework key wasn't present (e.g., framework normalization differences). Replaced with TryGetValue + fallback to highest available version.

• Min() on empty sequence: When all package version strings were unparseable, currentMin computation crashed. Now guards with an early-out warning.

• PackageInfoComparer null TargetFrameworks: Equality check short-circuited to false when either side had null TargetFrameworks, causing duplicate container entries and missed updates.

// Before: null on either side → always false → duplicates
(x.TargetFrameworks != null && y.TargetFrameworks != null &&
 x.TargetFrameworks.SequenceEqual(...))

// After: both-null is equal, mixed-null is not
((x.TargetFrameworks == null && y.TargetFrameworks == null) ||
 (x.TargetFrameworks != null && y.TargetFrameworks != null &&
  x.TargetFrameworks.SequenceEqual(...)))

Output improvements

• Console tables: Consistent header capitalization (Current/Latest/Target/Reason)
• Markdown tables: Column-aligned with padding, proper pipe spacing

Cleanup

• Removed misleading // no support for slnx comment (slnx was supported)
• Removed unused imports (System.Net.NetworkInformation, System.Linq)
• Added null-safety check for result.TargetFrameworkVersions

Tests

13 new tests covering PackageInfoComparer null handling, MarkdownTableFormatter alignment/escaping, and NuGetMetadataService stable-version preference. All 115 tests pass.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.