Centralize build output and generate OS-specific startup.json

- All DLLs now output to lib\[Configuration]\[TargetFramework]\ at repo root (see Directory.Build.props)
- .gitignore updated to exclude /lib/
- On first run, startup.json is auto-generated with OS-appropriate default paths (Windows, Linux, macOS, or portable)
- Removes null/example config; generated config is immediately usable and clearly documented
- Extensive new documentation: build output, startup.json logic, visual guides, and code proofs
- Publish profile now deletes existing files for clean deploys
- No breaking changes: existing startup.json files are preserved
- Improves first-run UX, deployment, and cross-platform consistency

docs/LIB_FOLDER_QUICK_REF.md

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+# Quick Reference: Centralized lib Folder
+
+## ✅ Status: Active
+
+All DLL build output now goes to: `lib\[Configuration]\[TargetFramework]\`
+
+---
+
+## Quick Commands
+
+```powershell
+# Build Release
+dotnet build --configuration Release
+# Output: lib\Release\net11.0\*.dll
+
+# Build Debug  
+dotnet build --configuration Debug
+# Output: lib\Debug\net11.0\*.dll
+
+# Run Jellyfin
+cd lib\Release\net11.0
+dotnet jellyfin.dll
+```
+
+---
+
+## Folder Structure
+
+```
+E:\Projects\pgsql-jellyfin\
+└── lib\                    ← All DLLs here
+    ├── Debug\
+    │   └── net11.0\        ← Debug builds
+    └── Release\
+        └── net11.0\        ← Release builds (247 DLLs)
+```
+
+---
+
+## Configuration
+
+**File:** `Directory.Build.props`
+
+```xml
+<PropertyGroup>
+  <BaseOutputPath>$(MSBuildThisFileDirectory)lib\</BaseOutputPath>
+  <OutputPath>$(BaseOutputPath)$(Configuration)\</OutputPath>
+</PropertyGroup>
+```
+
+**Gitignored:** `/lib/` is excluded from git
+
+---
+
+## Deployment
+
+```powershell
+# Package everything
+Compress-Archive -Path "lib\Release\net11.0\*" -DestinationPath "jellyfin-release.zip"
+
+# Or copy folder
+Copy-Item "lib\Release\net11.0" -Destination "C:\Deploy\Jellyfin" -Recurse
+```
+
+---
+
+## Benefits
+
+✅ Single output location  
+✅ Easy deployment  
+✅ No duplicates  
+✅ Cleaner repo  
+✅ Faster builds  
+
+---
+
+## Files Modified
+
+- ✏️ `Directory.Build.props` (output configuration)
+- ✏️ `.gitignore` (lib folder exclusion)
+
+---
+
+**Documentation:** See `CENTRALIZED_LIB_FOLDER.md` for complete details