chore(linting): refresh configs and sweep auto-fix

Pull in the refreshed linter and tooling configs (editorconfig,
gitignore, gitattributes, prettierignore, prettierrc, markdownlint,
yamllint, env.example, dotnet-tools) and run prettier and markdownlint
in --fix / --write mode across the repo so the existing tree matches
the new rules.

- prettier 2-space indent on yaml/yml and json overrides, asterisk
  strong, underscore emphasis, proseWrap always
- markdownlint MD007 indent aligned to 2 and MD049 to underscore so
  prettier output stays passing
- preflight Block F also ignores CLAUDE.md (gitignored personal file)
- prettierignore extended to keep HellionChat.yaml manifest and the
  NuGet packages.lock.json out of the formatter

No semantic content changed; csharpier, build, full build-suite
(729/729) and the new prettier/markdownlint/yamllint checks all green.

.github/PULL_REQUEST_TEMPLATE.md

@@ -18,7 +18,8 @@ mailto:kontakt@hellion-media.de?subject=%5BHellionChat%20Security%5D
 
 - [ ] Bug fix (non-breaking change that fixes an issue)
 - [ ] New feature (non-breaking change that adds behaviour)
-- [ ] Breaking change (config migration, removed feature, or behaviour change that user-visible defaults rely on)
+- [ ] Breaking change (config migration, removed feature, or behaviour change that user-visible
+      defaults rely on)
 - [ ] Documentation only
 - [ ] Translation update
 - [ ] Build, CI or tooling change
@@ -55,10 +56,11 @@ new commands, new translations, removed behaviour. If none, write
 
 ## Checklist
 
-- [ ] I have read [CONTRIBUTING.md](../CONTRIBUTING.md) and [CODE_OF_CONDUCT.md](../CODE_OF_CONDUCT.md).
+- [ ] I have read [CONTRIBUTING.md](../CONTRIBUTING.md) and
+      [CODE_OF_CONDUCT.md](../CODE_OF_CONDUCT.md).
 - [ ] My change matches the existing code style (`.editorconfig`).
-- [ ] I added or updated tests where the existing test infrastructure made that practical, or I have explained why tests
-      are not applicable.
+- [ ] I added or updated tests where the existing test infrastructure made that practical, or I have
+      explained why tests are not applicable.
 - [ ] I updated the README, in-plugin strings or documentation if my change is user-visible.
 - [ ] I did not include any AI-generated code without disclosing it in the PR description (see
       [AI_DISCLOSURE.md](../docs/AI_DISCLOSURE.md)).