Rewrite Miniflux plugin to use requests, add filter and bookmark tools

Drop the miniflux pip client in favour of requests (already in the
container). Add update_feed_filters (keeplist/blocklist regex),
toggle_bookmark, get_entry (full content), and category filtering.
Remove the pip install step from Ansible.

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

infra/ansible/playbook.yml

@@ -399,6 +399,7 @@
         chdir: /opt/hermes
       tags: hermes
 
+
     # ── GoatCounter ─────────────────────────────────────────────────────────
 
     - name: Create goatcounter system user