!explain via ❓ reaction: thread-reply with a 3-bullet TL;DR

When a user reacts ❓ on one of Pete's posts, fetch the article body,
ask Ollama for a 3-bullet summary, and post it as a threaded reply
rooted at the original story event. Per-process cooldown of 5min per
story keeps repeated reactions from re-summarizing.

- ingestion.FetchArticleBody: visible <p> text capped at 8000 chars
- classifier.OllamaClient.GenerateText: non-JSON variant
- storage.GetStoryByGUID: full row lookup
- matrix.PostThreadedReply: m.thread + m.in_reply_to fallback
- poster.SetReactionCallback: optional hook fired after recording
- New package: internal/explainer

internal/classifier/ollama.go

@@ -51,20 +51,28 @@ func NewOllamaClient(cfg config.OllamaConfig) *OllamaClient {
 
 // Generate sends a prompt to Ollama via the chat API and returns the raw response text.
 func (o *OllamaClient) Generate(prompt string) (string, error) {
+	return o.call(
+		"You are a JSON-only news classification API. Respond with valid JSON only. No preamble, no explanation, no markdown.",
+		prompt,
+		"json",
+	)
+}
+
+// GenerateText sends a system + user prompt to Ollama and returns the raw
+// text response. Unlike Generate, no JSON mode is forced.
+func (o *OllamaClient) GenerateText(systemPrompt, userPrompt string) (string, error) {
+	return o.call(systemPrompt, userPrompt, "")
+}
+
+func (o *OllamaClient) call(systemPrompt, userPrompt, format string) (string, error) {
 	reqBody := chatRequest{
 		Model: o.model,
 		Messages: []chatMessage{
-			{
-				Role:    "system",
-				Content: "You are a JSON-only news classification API. Respond with valid JSON only. No preamble, no explanation, no markdown.",
-			},
-			{
-				Role:    "user",
-				Content: prompt,
-			},
+			{Role: "system", Content: systemPrompt},
+			{Role: "user", Content: userPrompt},
 		},
 		Stream: false,
-		Format: "json",
+		Format: format,
 	}
 
 	body, err := json.Marshal(reqBody)