Add Roslyn analyzer (Waffle.Analyzer) for compile-time template syntax validation

[Rijicho]

Summary

Adds a new Roslyn analyzer package Waffle.Analyzer that inspects the interpolated string arguments passed to WaffleSyntax.Render / RenderCSharp at compile time. Template structure violations that previously surfaced only at runtime — such as unclosed blocks, out-of-scope loop variables, and misplaced control commands — are now reported as build errors and IDE diagnostics.

Related Issue

Closes #9

Changes

• src/Waffle.Analyzer/ — new analyzer project (Waffle.Analyzer.csproj)
  • WaffleTemplateAnalyzer — DiagnosticAnalyzer that detects WaffleSyntax.Render / RenderCSharp call sites and dispatches analysis on their interpolated string arguments
  • TemplateBlockWalker — walks block structure, variable scope, and control-command consistency
  • WaffleDiagnostics — diagnostic rule definitions for WAF001–WAF007
• tests/Waffle.Analyzer.Test/ — test project covering pass and fail cases for every rule
• README.md — added Waffle.Analyzer badge and package table entry
• src/Waffle.Analyzer/README.md — analyzer-specific README
• .github/workflows/release.yml — added Waffle.Analyzer to the release workflow
• Waffle.sln — added new projects to the solution

Checklist

• All existing tests pass (dotnet test -c Debug)
• New functionality is covered by tests
• This PR targets the main branch

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