docs: add IDE debugging setup guide

[fpindej]

Summary

Add a docs/debugging.md (or expand docs/development.md) with step-by-step IDE debugging setup for the three major .NET IDEs. Currently development.md has one line about Rider and nothing for VS Code or Visual Studio.

Related: #179 (.editorconfig) — these complement each other for a complete IDE experience.

Scope

JetBrains Rider

• Launch profile setup (use existing launchSettings.json)
• How to debug backend while frontend runs in Docker:
  1. Stop the API container: ./deploy/up.sh local stop api
  2. Set API_URL=http://host.docker.internal:<port> in frontend env
  3. Run/debug from Rider with the Development profile
• Attach to running Docker container (remote debugging)
• Database tool window connection to Docker PostgreSQL
• Recommended plugins (if any)

Visual Studio

• Same workflow as Rider but with VS-specific screenshots/steps
• Docker Compose integration (VS has built-in support)
• Launch profile selection
• Debugging with Hot Reload

VS Code

• launch.json configuration for .NET debugging (C# Dev Kit)
• tasks.json for build tasks
• Recommended extensions: C# Dev Kit, Svelte for VS Code, Tailwind CSS IntelliSense, ESLint, Prettier
• Frontend debugging with browser DevTools (Svelte DevTools extension)
• Compound launch configs (backend + frontend simultaneously)

General tips

• How to set breakpoints in middleware (exception handling, auth)
• How to inspect EF Core SQL queries (Serilog + Seq)
• How to debug background jobs (Hangfire dashboard)
• How to test email sending locally (Seq logs NoOp output)

Notes

• Keep it practical — exact steps, not theory
• Include launchSettings.json snippets where needed
• Reference the host.docker.internal pattern already documented in compose files