Add Microsoft.Extensions.Logging.Abstractions to Confuser.Core
(netstandard2.0 compatible) and a MelLoggerAdapter that bridges
M.E.L ILogger to the internal Confuser.Core.ILogger interface.

This allows callers to pass a standard M.E.L logger (backed by
Serilog or any other provider) into ConfuserEngine without
changing any internal code yet.

Wire up Serilog as the logging provider in the CLI via
Microsoft.Extensions.Logging and MelLoggerAdapter.

- Add Serilog, Serilog.Extensions.Logging, Serilog.Sinks.Console
- Delete custom ConsoleLogger — Serilog handles all console output
- Add --verbose (-v, -vv, -vvv) and --quiet (-q) CLI flags
- Default: Information level; -q: Warning; -v: Debug; -vv+: Verbose

Wire up Serilog in the WPF GUI via a custom FlowDocumentSink that
renders color-coded log output to the protection log panel.

- Add Serilog and Serilog.Extensions.Logging to ConfuserEx
- Create FlowDocumentSink — custom Serilog sink for WPF Paragraph
- Remove ILogger from ProtectTabVM — now uses MelLoggerAdapter
- ProtectTabVM keeps only IProgressReporter (progress bar + finish)
- Delete ~40 lines of manual ILogger boilerplate

Full local CI script that replicates lint.yml, ci.yml, and test.yml:
- lint: whitespace, style, and analyzer checks via dotnet format
- build: dotnet build for SDK projects + MSBuild.exe for C++/CLI
- test: discovers all *.Test.csproj, runs with coverage, summary
- package: creates CLI, GUI, and combined zip archives

Usage: ./scripts/local-ci.sh [lint|build|test|package|all]

…ging.ILogger (#64)

Complete migration from the custom 13-method ILogger interface to the
standard M.E.L ILogger abstraction across all projects.

- Change ConfuserContext.Logger and ConfuserParameters.Logger to M.E.L ILogger
- Convert all ~80 call sites: Debug→LogDebug, Info→LogInformation,
  Warn→LogWarning, Error→LogError, *Exception→swap parameter order
- Rewrite MSBuildLogger as MSBuildMelLogger implementing M.E.L ILogger
- Rewrite XUnitLogger implementing M.E.L ILogger + IProgressReporter
- Remove MelLoggerAdapter (no longer needed — M.E.L is the native type)
- Delete Confuser.Core.ILogger, NullLogger (replaced by M.E.L NullLogger)
- Add test-results/ and coverage/ to .gitignore

DoProtect used 'using var loggerFactory' which disposed the factory
(and the Serilog logger via dispose:true) as soon as DoProtect returned.
Since ConfuserEngine.Run executes asynchronously on a background thread,
this disposed the logger before the protection actually used it, silently
dropping log output mid-run. Move disposal into the ContinueWith
continuation so the factory lives for the full protection lifetime.

Gui_ProtectSampleApp_ShowsSuccess intermittently failed at the Protect!
button lookup (~1 in 3 runs). Two root causes:

1. ByText("Protect!") ambiguously matched both the tab header and the
   Protect! button (they share the caption), so the wrong element could
   be clicked and the tab never actually got selected.
2. WPF virtualizes inactive tab content — the Protect! button does not
   enter the UIA tree until the tab is selected AND rendered. The 5s
   button-find timeout was too short under load.

Fix: match the tab by TabItem control type + name, Select() it and wait
for IsSelected, then find the button with a 15s timeout. 5/5 consecutive
full-suite runs now pass 3/3 (previously ~1/3 failed).