v1.1.0: enkel globaal filter (config) in plaats van per-subscription

- match_filter is nu instance-config (geldt voor ALLE feeds), niet per
  subscription: !rss set-filter <regex> zet het globale filter en slaat
  config op; !rss subscriptions toont het globale filter
- v7-migratie: per-subscription kolom match_filter verwijderd
- filter scant titel + HTML-ontdaan summary

base-config.yaml

@@ -15,9 +15,9 @@ notification_template: "New post in $feed_title: [$title]($link)"
 # Should non-admin users be allowed to set regex filters to drop posts from feeds?
 # Regexes are dangerous and may lead to DoS attacks.
 allow_filter: false
-# Per-subscription match filter (whitelist): set with `!rss set-filter <feed-id> <regex>`.
+# Global match filter (whitelist): applies to ALL feeds in this instance.
 # A post is ONLY sent when the regex matches the title OR the (HTML-stripped) summary.
-# Empty = fall back to the default below.
+# Set it live with `!rss set-filter <regex>`. Empty = send everything.
 match_filter: "(?i)\\b(?:gvb|ebs|connexxion|cxx|transdev|keolis|ret|gvu|bus|metro|tram|ov)\\b|trein(?:en|verkeer|stel(?:len)?|staking|ongeluk)?|\\bov-staking|staking"
 # Users who can bypass room permission checks
 admins: