Apply no-nested-functions rule to all functions

Move the nested helper guidance from the private-functions section to general layout rules so it clearly applies to all functions.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

src/docs/Modules/Standards.md

@@ -42,6 +42,7 @@ Layout rules:
 - **One declaration per file.** Filename matches the declared symbol exactly, including casing.
 - **Group by domain.** Use resource or behaviour groups — not verb folders, not endpoint paths.
 - **Mirror public and private domains.** Public command under `src/functions/public/Projects/` has related private helpers under `src/functions/private/Projects/`.
+- **No nested functions.** Do not define helper functions inside other functions. Put helper logic in separate private function files under `src/functions/private/<Group>/`.
 - **Declare dependencies where they are used.** Use `#Requires -Modules <Name>` at the top of each function file that needs an external module. Do not add `RequiredModules` to `src/manifest.psd1` — the build collects all `#Requires` declarations automatically and writes them into the compiled manifest. Entries in `src/manifest.psd1` are silently ignored for this purpose.
 - **Group documentation pages with source.** Place a `<Group>.md` file alongside the function files in each `src/functions/public/<Group>/` folder to provide a category overview in generated documentation.
 
@@ -57,7 +58,6 @@ Layout rules:
 - No pipeline input.
 - No defaulting from context — public callers resolve before calling.
 - Required inputs declared as mandatory.
-- No nested helper functions. If logic needs a helper, create it as a separate private function file under `src/functions/private/<Group>/`.
 
 ## SOLID applied