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

- `.env.production.sample`:
  Our sample config file is very different from upstream since it is much more
  complete. Upstream added documentation for a few env variables.
  Copied the new variables/documentation from upstream.
- `app/lib/feed_manager.rb`:
  Upstream added a timeline type (hashtags), while glitch-soc already had an
  extra one (direct messages). Not really a conflict but textually close
  changes.
  Ported upstream's changes.
- `app/models/custom_emoji.rb`:
  Upstream upped the custom emoji size limit, while glitch-soc had configurable
  limits.
  Upped the default limits accordingly.
- `streaming/index.js`:
  Upstream reworked how hastags were normalized. Minor conflict due to
  glitch-soc's handling of instance-local posts.
  Ported upstream's changes.

.env.production.sample

@@ -289,3 +289,11 @@ MAX_REMOTE_EMOJI_SIZE=204800
 # Optional hCaptcha support
 # HCAPTCHA_SECRET_KEY=
 # HCAPTCHA_SITE_KEY=
+
+# IP and session retention
+# -----------------------
+# Make sure to modify the scheduling of ip_cleanup_scheduler in config/sidekiq.yml
+# to be less than daily if you lower IP_RETENTION_PERIOD below two days (172800).
+# -----------------------
+IP_RETENTION_PERIOD=31556952
+SESSION_RETENTION_PERIOD=31556952