Migrate from SQLite to PostgreSQL

- Replace modernc.org/sqlite with jackc/pgx/v5
- Update all SQL queries for PostgreSQL syntax ($1, $2 placeholders)
- Use snake_case column names throughout
- Replace SQLite FTS5 with PostgreSQL tsvector/tsquery full-text search
- Add connection pooling with pgxpool
- Support Docker secrets for database password
- Add trigger to normalize feed URLs (strip https://, http://, www.)
- Fix anchor feed detection regex to avoid false positives
- Connect app container to atproto network for PostgreSQL access
- Add version indicator to dashboard UI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

html.go

@@ -77,7 +77,11 @@ func (c *Crawler) extractFeedLinks(n *html.Node, baseURL string) []simpleFeed {
 
 func (c *Crawler) extractAnchorFeeds(n *html.Node, baseURL string) []simpleFeed {
 	feeds := make([]simpleFeed, 0)
-	feedPattern := regexp.MustCompile(`(?i)(rss|atom|feed)`)
+	// Match feed URLs more precisely:
+	// - /feed, /rss, /atom as path segments (not "feeds" or "feedback")
+	// - .rss, .atom, .xml file extensions
+	// - ?feed=, ?format=rss, etc.
+	feedPattern := regexp.MustCompile(`(?i)(/feed/?$|/feed/|/rss/?$|/rss/|/atom/?$|/atom/|\.rss|\.atom|\.xml|\?.*feed=|\?.*format=rss|\?.*format=atom)`)
 
 	var f func(*html.Node)
 	f = func(n *html.Node) {