Use plugin-helper profiles in builder skill

.agents/skills/beatsaber-plugin-builder/references/linux-bsipa-build.md

@@ -6,7 +6,8 @@ This workflow comes from `/home/pleb/ops/beatsaber/setlist/docs/pc-modding.md` a
 
 ## Toolchain
 
-- PC BSIPA plugins are usually .NET Framework `net472` class libraries.
+- PC BSIPA plugins are .NET Framework class libraries; current projects
+  commonly target `net48`, while older projects may still target `net472`.
 - Linux `dotnet` SDK 6+ can build them because output DLLs are platform-agnostic CIL loaded by Beat Saber under Proton.
 - `BeatSaberModdingTools.Tasks` supplies the MSBuild targets normally driven by Visual Studio/Rider BSMT extensions.
 - On this host, `dotnet --list-sdks` should show a usable SDK. NuGet is available for package inspection.
@@ -24,16 +25,13 @@ Plugins/
 winhttp.dll
 ```
 
-Preferred local managed instance root:
+In `plugin-helper`, prefer the profile selected from
+`plugin-helper.local.toml` as the source of truth for the managed instance root
+and state directory:
 
-```text
-/home/pleb/.local/share/BSManager/BSInstances/<version>
-```
-
-Windows mirror root:
-
-```text
-/home/pleb/Windows/Users/pleb/BSManager/BSInstances/<version>
+```bash
+sed -n '1,220p' plugin-helper.local.toml
+PYTHONPATH=src .venv/bin/python -m plugin_helper --profile <profile-id> instances
 ```
 
 Use `BeatSaberVersion.txt` for the exact game version. The manifest `gameVersion` normally uses the `major.minor.patch` prefix, not the build suffix.
@@ -45,7 +43,7 @@ Prefer machine-local configuration in `<Project>.csproj.user`:
 ```xml
 <Project>
   <PropertyGroup>
-    <BeatSaberDir>/home/pleb/.local/share/BSManager/BSInstances/1.40.8</BeatSaberDir>
+    <BeatSaberDir>/path/from/selected/profile/instances_root/1.44.1</BeatSaberDir>
   </PropertyGroup>
 </Project>
 ```
@@ -60,7 +58,10 @@ For those, pass `-p:LocalRefsDir=/path/to/instance` or add a local `.csproj.user
 
 When changing a project file for Linux portability, prefer the smallest explicit fix:
 
-- Add `Microsoft.NETFramework.ReferenceAssemblies.net472` when MSBuild reports missing .NET Framework reference assemblies.
+- Add the `Microsoft.NETFramework.ReferenceAssemblies.*` package matching the
+  project target framework, usually `Microsoft.NETFramework.ReferenceAssemblies.net48`
+  for current projects, when MSBuild reports missing .NET Framework reference
+  assemblies.
 - Set or pass `DisableCopyToPlugins=True` for artifact-only builds.
 - Keep hint paths rooted at `$(BeatSaberDir)` where possible.
 - Do not add broad multi-version compatibility logic unless requested.
@@ -105,7 +106,9 @@ If the purpose is to install the built artifact, copy it into plugin-helper's st
 
 ## Common Reference Failures
 
-- `MSB3644` or missing `.NETFramework,Version=v4.7.2` reference assemblies: add `Microsoft.NETFramework.ReferenceAssemblies.net472`.
+- `MSB3644` or missing `.NETFramework,Version=v4.x` reference assemblies: add
+  the matching `Microsoft.NETFramework.ReferenceAssemblies.*` package, usually
+  `Microsoft.NETFramework.ReferenceAssemblies.net48` for current projects.
 - Missing game assemblies such as `Main.dll`, `HMUI.dll`, `UnityEngine.CoreModule.dll`: `BeatSaberDir` is wrong or incomplete.
 - Missing mod dependencies such as `BSML.dll`, `SongCore.dll`, `SiraUtil.dll`, `BeatSaberPlaylistsLib.dll`: install or point at an instance containing those plugins, or fetch the dependency DLL from its verified release only when appropriate.
 - `IPA.Loader.dll` missing: BSIPA is not bootstrapped in that instance.
@@ -115,17 +118,17 @@ If the purpose is to install the built artifact, copy it into plugin-helper's st
 For a built plugin DLL intended for a managed instance:
 
 ```bash
-mkdir -p .state/instances/<instance>/downloads/<plugin-id>
-cp <checkout>/<path>/bin/Release/<Plugin>.dll .state/instances/<instance>/downloads/<plugin-id>/<Plugin>.dll
-sha256sum .state/instances/<instance>/downloads/<plugin-id>/<Plugin>.dll
+mkdir -p <state_dir>/instances/<instance>/downloads/<plugin-id>
+cp <checkout>/<path>/bin/Release/<Plugin>.dll <state_dir>/instances/<instance>/downloads/<plugin-id>/<Plugin>.dll
+sha256sum <state_dir>/instances/<instance>/downloads/<plugin-id>/<Plugin>.dll
 ```
 
 Then update registry/lock data only if the user asked to manage/install the artifact, and use:
 
 ```bash
-PYTHONPATH=src python -m plugin_helper --state-dir .state check --instance <instance>
-PYTHONPATH=src python -m plugin_helper --state-dir .state plan --instance <instance> --plugin <plugin-id>
-PYTHONPATH=src python -m plugin_helper --state-dir .state apply <plan-path>
+PYTHONPATH=src .venv/bin/python -m plugin_helper --profile <profile-id> check --instance <instance>
+PYTHONPATH=src .venv/bin/python -m plugin_helper --profile <profile-id> plan --instance <instance> --plugin <plugin-id>
+PYTHONPATH=src .venv/bin/python -m plugin_helper --profile <profile-id> apply <plan-path>
 ```
 
 Inspect the generated plan before applying.