Lots of features, first version that reliably crawls Geminispace.

- [x] Concurrent downloading with workers
- [x] Concurrent connection limit per host
- [x] URL Blacklist
- [x] Save image/* and text/* files
- [x] Configuration via environment variables
- [x] Storing snapshots in PostgreSQL
- [x] Proper response header & body UTF-8 and format validation
.

.

error_urls.txt

@@ -0,0 +1,8 @@
+// body with null byte
+gemini://kennedy.gemi.dev/archive/cached?url=gemini://spam.works/mirrors/textfiles/fun/consult.how&t=638427244900000000&raw=False
+
+// has invalid url
+gemini://tlgs.one/known-hosts
+
+// Needs SNI TLS info (our bug)
+gemini://hanzbrix.pollux.casa/gemlog/20241002.gmi