fix: format token counts consistently with K/M/B units

[coldhighsun]

Summary

• Format token counts in the CLI's bar charts (Tokens by Model, Daily Tokens, Tokens by Hour) with the same K/M/B scaling already used in the stats tables, instead of raw N0 numbers.
• Fix the WPF hourly-activity chart's Y-axis labeler to use the shared FormatTokens helper instead of raw N0 formatting.
• Update CLAUDE.md and README.md docs (watch command, MinVer versioning notes, release pipeline, badges) and add NuGet package tags to the CLI csproj.

Test plan

• dotnet build AIUsageMonitor.slnx succeeds
• Reviewed unit scaling per chart (Hourly series uses raw tokens, Daily series uses tokens/1e6) to confirm formatter calls match their series' units