Conformance: modernize CODESTYLE.md to the template structure

[ptr727]

Context

This repo's CODESTYLE.md predates the template's General/.NET/Python restructure (ptr727/ProjectTemplate CODESTYLE.md). Its content still works but the organization has diverged, only because the template restructure was never propagated here. (The narrow spelling-rule fix — US-English + CI scope — already landed in #11.)

Goal

Reorganize CODESTYLE.md into the template's structure — General + .NET (this repo is csharp / console / docker) — adapted to this repo's actuals. Do NOT copy the template verbatim: it describes the template's own specifics.

This repo's actuals (make the doc match reality)

• VS Code task labels are .Net Build / .Net Format (this repo's casing), not the template's .NET .... Keep doc and .vscode/tasks.json consistent (match one to the other).
• Confirm the actual analyzer settings in the .csproj/props — the template asserts <AnalysisMode>All</AnalysisMode> + <TreatWarningsAsErrors>true</TreatWarningsAsErrors>; only state what this repo really sets.
• PhotoCleaner.code-workspace currently holds a cSpell.words list; the template rule says the word list must live in cspell.json. Reconcile (move it) or describe the actual setup.
• Tests use Assert.Skip(...) to skip when external tools are unavailable — the template forbids native xUnit asserts; carve out this legitimate exception or adjust the rule text.
• The template's LanguageTags / LogOptions code examples don't exist here — replace with repo-real examples or mark as illustrative.
• Markdown here is CRLF (.editorconfig); keep any rewrite CRLF.

Reference

• Template CODESTYLE.md = structure/rules source (adapt, don't clone).
• A verbatim modernization was attempted in Modernize CODESTYLE to the canonical structure #12 (now closed); Copilot's inline notes there enumerate the mismatches above.

[ptr727]

Current state (audit run 2026-07-18T15:27:40Z | hub 7a3905b)

Still valid - CODESTYLE.md exists but carries pre-template sections (Build Requirements / Tooling and Editor / Coding Standards and Conventions / Project Configuration / Structured Logging), not the current General + per-language structure. Wider than the title: both rulesets are missing entirely and 8 baseline files are absent.

Live findings for this repo from the hub fleet audit:

== PhotoCleaner (csharp, console, docker; release) @ develop@6eaf1cb ==
  DEFECT ruleset: develop missing
  DEFECT ruleset: main missing
  LETTER file: WORKFLOW.md absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: version.json absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: repo-config/develop.json absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: repo-config/main.json absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: AUDIT.md absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: spec/secrets.json absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: .github/dependabot.yml absent on develop (verify intent per AUDIT.md section 7)
  LETTER file: Docker/README.md absent on develop (verify intent per AUDIT.md section 7)

Per AUDIT.md section 8, this block is a point-in-time snapshot: re-run python3 spec/audit.py PhotoCleaner from the hub and act on the live result, not on these pasted findings.

[ptr727]

Covered by the round-1 governance carry: PR #16 (squash 50a524e) re-vendored CODESTYLE.md from the hub canonical (template structure, General + .NET sections, repo-adapted InternalsVisibleTo names), and the round-2 canonical refresh keeps it at parity with the hub's current text. Closing per issue #14 item 7.