📖 [Docs]: Rename Repository-Defaults to Repository Standard and align with MSX

[MariusStorhaug]

The PSModule organization's repository-standard documentation is renamed from "Repository Defaults" to "Repository Standard" and aligned to the MSX Enterprise Repository Standard, so PowerShell module repositories are governed by a standard that sits at the same altitude as MSX and only adds or adjusts the MSX default where module repositories need it.

Context and request

src/docs/Modules/Repository-Defaults.md currently frames itself as "repository defaults" and lists required baseline files that no longer match the MSX Enterprise Repository Standard (it still requires .github/copilot-instructions.md, .github/release.yml, and the linter config files). The page should become the PSModule Repository Standard, state its altitude relative to MSX, and correct the required-files set.

Acceptance criteria:

• src/docs/Modules/Repository-Defaults.md is renamed to src/docs/Modules/Repository-Standard.md with history preserved (git mv).
• Every reference to the old filename/label is updated: src/zensical.toml nav, src/docs/Modules/index.md, src/docs/Modules/Module-Types.md, and src/docs/Modules/Process-PSModule/module-build-validation.md.
• H1 becomes # Repository Standard; self-referential "repository defaults" prose that names the page is updated to "repository standard".
• Scope states this is the PSModule organization's Repository Standard for PowerShell module repositories.
• An altitude/layering statement explains that this standard sits at the same altitude as MSX and adds to/adjusts the MSX default, with a link to the MSX Repository Standard.
• Required-files edits are applied in both the layout table and the required common files table: remove .github/copilot-instructions.md, .github/release.yml, and the two .github/linters/* rows; keep .github/PSModule.yml; reword pull_request_template.md, .gitattributes, .gitignore, and dependabot.yml.
• AGENTS.md and CLAUDE.md remain required; the Agent onboarding files section does not reintroduce copilot-instructions.
• Doc lint/build passes with no broken links introduced by the rename.

Non-goals: rewriting README defaults, Managed file distribution meaning, or the Supply-chain dependabot example.

Technical decisions

• Cross-repo link to MSX uses the site convention already used in this repo: https://msxorg.github.io/docs/Ways-of-Working/Repository-Standard/.
• The PSModule org has no Docs issue type; this issue uses the Task type (single reviewable deliverable) with the 📖 [Docs] change-type framing in the title.
• Delivered as one branch and one draft PR in MSX PR Format with micro-commits (no conventional-commit prefixes).

Implementation plan

• git mv the file and update all nav/index/link references to the new filename and label.
• Update H1, scope, and add the altitude/layering statement + MSX link.
• Apply required-files table removals and rewordings in both tables.
• Run doc lint/build and fix any link/lint failures introduced by the rename.