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.

SECURITY.md

@@ -2,8 +2,8 @@
 
 ## Reporting a Vulnerability
 
-If you find a security issue in HellionChat, please do not open a public Gitea issue. Use one of the private channels
-below so I can investigate and ship a fix before the details go public.
+If you find a security issue in HellionChat, please do not open a public Gitea issue. Use one of the
+private channels below so I can investigate and ship a fix before the details go public.
 
 **Preferred:**
 
@@ -20,7 +20,8 @@ I respond on weekdays during European business hours.
 
 ### In scope
 
-- Code paths that touch user-controlled input (chat messages, plugin config, file paths the user can influence)
+- Code paths that touch user-controlled input (chat messages, plugin config, file paths the user can
+  influence)
 - The privacy filter in `MessageStore.cs` and the export pipeline
 - The configuration migration logic
 - The `EmoteCache` HTTP client and path handling
@@ -36,10 +37,10 @@ I respond on weekdays during European business hours.
 
 ## Disclosure Window
 
-I aim to ship a fix within 14 days for high-severity issues and within 30 days for everything else. If a fix needs more
-time I will say so in the private thread.
+I aim to ship a fix within 14 days for high-severity issues and within 30 days for everything else.
+If a fix needs more time I will say so in the private thread.
 
 ## Credits
 
-Everyone who reports a real issue gets listed in the changelog of the release that fixes it, unless they prefer to stay
-anonymous. No bug bounty, nothing financial — this is a hobby plugin.
+Everyone who reports a real issue gets listed in the changelog of the release that fixes it, unless
+they prefer to stay anonymous. No bug bounty, nothing financial — this is a hobby plugin.