Add project README and reason/quote fields to classifier response

- README.md: full project overview with setup, training, API, and RSpamd integration docs
- server.py: add reason (human-readable explanation) and quote (suspicious snippet) to response
- spamllm.lua: pass reason and quote through to RSpamd symbol description for logs/UI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

rspamd/lua/spamllm.lua

@@ -75,9 +75,14 @@ local function check_spamllm(task)
     local result = parser:get_object()
 
     if result.is_spam then
-      task:insert_result(settings.symbol_spam, result.confidence, "SpamLLM")
-      rspamd_logger.infox(task, "SpamLLM: SPAM (confidence=%.2f, score=%.2f, lang=%s)",
-        result.confidence, result.score, result.language or "?")
+      -- Reason und Quote als Options an das Symbol anhängen
+      local description = result.reason or "SpamLLM"
+      if result.quote and #result.quote > 0 then
+        description = description .. " | " .. result.quote
+      end
+      task:insert_result(settings.symbol_spam, result.confidence, description)
+      rspamd_logger.infox(task, "SpamLLM: SPAM (confidence=%.2f, score=%.2f, lang=%s, reason=%s)",
+        result.confidence, result.score, result.language or "?", result.reason or "?")
     else
       task:insert_result(settings.symbol_ham, -result.confidence, "SpamLLM")
     end