stacks/miniflux: self-hosted RSS reader + News group on homepage

Adds Miniflux on ana-docker as the unified inbox for tech blogs,
Hacker News, lobste.rs, and selected subreddits. Reddit serves clean
RSS for any sub at https://reddit.com/r/<sub>/.rss, so subreddit
follows fold into the same inbox as everything else — no Reddit
account needed, no manual polling.

Stack:
  stacks/miniflux/
    compose.yaml          — miniflux + bundled postgres:16
    .env.example          — placeholders for DB password + admin user
    starter-feeds.opml    — initial subscriptions (HN, Lobste.rs,
                            r/selfhosted, r/homelab, r/LocalLLaMA, r/nba)
    README.md             — deploy / OPML import / r/nba spoiler
                            block-list / backup / update flow

Postgres bundled with the stack (not pfi-postgres) — single-user RSS
DB is tiny and the bundle keeps the dependency graph flat.

Homepage gets a new 'News' group at the TOP of the Main tab (above
Monitoring) so the Miniflux card sits prominently. The card itself
auto-discovers via the homepage.* labels on the miniflux container.

Per-feed block-list rule for r/nba documented in README — Reddit's
RSS titles for game threads include scores ("Lakers 108 - Warriors
102 [Final]") which spoil the game; a regex catches the score
patterns and skips those entries while keeping discussion/highlights.

Deploy:
  scripts/elway ana-docker --playbook playbooks/deploy-miniflux.yaml

Then edit /opt/docker/compose/miniflux/.env on the host to fill in
the two CHANGE_ME passwords and `docker compose up -d` again.

configs/homepage/settings.yaml

@@ -35,6 +35,11 @@ useEqualHeights: true
 # Row counts target ~4-per-row so dense groups (Apps, Service Networking)
 # read as a grid instead of an endless column.
 layout:
+  News:
+    icon: mdi-rss
+    tab: Main
+    style: row
+    columns: 4
   Monitoring:
     icon: mdi-chart-line
     tab: Main