chore: prettier format all files, brotli, Sentry release tagging, CI gates

Prettier: auto-formatted 103 files to fix baseline. Prettier check in CI
  is now a hard gate (removed continue-on-error).

Brotli: installed libnginx-mod-http-brotli-filter/static. Enabled in nginx
  with brotli_static on for pre-compressed assets and comp_level 6.

Sentry releases: deploy script now exports VITE_APP_VERSION=<git-short-sha>
  before building so each Sentry release maps to an exact commit.
  CI also passes github.sha as VITE_APP_VERSION.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CONTRIBUTING.md

@@ -5,6 +5,7 @@ First off, thanks for taking the time to contribute! ❤️
 All types of contributions are encouraged and valued. Please make sure to read the relevant section before making your contribution. It will make it a lot easier for us maintainers and smooth out the experience for all involved. The community looks forward to your contributions. 🎉
 
 > And if you like the project, but just don't have time to contribute, that's fine. There are other easy ways to support the project and show your appreciation, which we would also be very happy about:
+>
 > - Star the project
 > - Tweet about it (tag @cinnyapp)
 > - Refer this project in your project's readme
@@ -18,6 +19,7 @@ Bug reports and feature suggestions must use descriptive and concise titles and
 ## Pull requests
 
 > ### Legal Notice
+>
 > When contributing to this project, you must agree that you have authored 100% of the content, that you have the necessary rights to the content and that the content you contribute may be provided under the project license. You will also be asked to [sign the CLA](https://github.com/cinnyapp/cla) upon submiting your pull request.
 
 **NOTE: If you want to add new features, please discuss with maintainers before coding or opening a pull request.** This is to ensure that we are on same track and following our roadmap.
@@ -26,9 +28,9 @@ Bug reports and feature suggestions must use descriptive and concise titles and
 
 Example:
 
-|Not ideal|Better|
-|---|----|
-|Fixed markAllAsRead in RoomTimeline|Fix read marker when paginating room timeline|
+| Not ideal                           | Better                                        |
+| ----------------------------------- | --------------------------------------------- |
+| Fixed markAllAsRead in RoomTimeline | Fix read marker when paginating room timeline |
 
 It is not always possible to phrase every change in such a manner, but it is desired.
 
@@ -39,6 +41,7 @@ Also, we use [ESLint](https://eslint.org/) for clean and stylistically consisten
 **For any query or design discussion, join our [Matrix room](https://matrix.to/#/#cinny:matrix.org).**
 
 ## Helpful links
+
 - [BEM methodology](http://getbem.com/introduction/)
 - [Atomic design](https://bradfrost.com/blog/post/atomic-web-design/)
 - [Matrix JavaScript SDK documentation](https://matrix-org.github.io/matrix-js-sdk/index.html)