Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `.github/dependabot.yml`:
  Updated upstream, removed in glitch-soc to disable noise.
  Kept removed.
- `CODE_OF_CONDUCT.md`:
  Upstream updated to a new version of the covenant, but I have not read it
  yet, so kept unchanged.
- `Gemfile.lock`:
  Not a real conflict, one upstream dependency updated textually too close to
  the glitch-soc only `hcaptcha` dependency.
  Applied upstream changes.
- `app/controllers/admin/base_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/controllers/application_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/controllers/disputes/base_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/controllers/relationships_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/controllers/statuses_cleanup_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/helpers/application_helper.rb`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `app/javascript/mastodon/features/compose/components/compose_form.jsx`:
  Upstream added a highlight animation for onboarding, while we changed the
  max character limit.
  Applied our local changes on top of upstream's new version.
- `app/views/layouts/application.html.haml`:
  Minor conflict due to glitch-soc's theming system.
  Applied upstream changes.
- `stylelint.config.js`:
  Upstream added ignore paths, glitch-soc had extra ignore paths.
  Added the same paths as upstream.

app/controllers/accounts_controller.rb

@@ -7,8 +7,9 @@ class AccountsController < ApplicationController
   include AccountControllerConcern
   include SignatureAuthentication
 
+  vary_by -> { public_fetch_mode? ? 'Accept, Accept-Language, Cookie' : 'Accept, Accept-Language, Cookie, Signature' }
+
   before_action :require_account_signature!, if: -> { request.format == :json && authorized_fetch_mode? }
-  before_action :set_cache_headers
 
   skip_around_action :set_locale, if: -> { [:json, :rss].include?(request.format&.to_sym) }
   skip_before_action :require_functional!, unless: :whitelist_mode?
@@ -16,7 +17,7 @@ class AccountsController < ApplicationController
   def show
     respond_to do |format|
       format.html do
-        expires_in 0, public: true unless user_signed_in?
+        expires_in(15.seconds, public: true, stale_while_revalidate: 30.seconds, stale_if_error: 1.hour) unless user_signed_in?
 
         @rss_url = rss_url
       end