feature: Improve the LLM prompts for tag generation

This new prompt works well in gpt-4o-mini and llama3.1-8b.

packages/shared/prompts.ts

@@ -1,14 +1,16 @@
 export function buildImagePrompt(lang: string, customPrompts: string[]) {
   return `
-You are a bot in a read-it-later app and your responsibility is to help with automatic tagging.
-Please analyze the attached image and suggest relevant tags that describe its key themes, topics, and main ideas. The rules are:
+You're an expert image tagger. Given an input you generate an JSON object of the following format: { "tags": ["First tag", "Another tag", ...] }
+
+Only respond in this format! Write only the JSON data and nothing else. Do not write an explanation.
+
+- Suggest relevant tags that describe its key themes, topics, and main ideas.
 - Aim for a variety of tags, including broad categories, specific keywords, and potential sub-genres.
 - The tags language must be in ${lang}.
 - If the tag is not generic enough, don't include it.
 - Aim for 10-15 tags.
-- If there are no good tags, don't emit any.
-${customPrompts && customPrompts.map((p) => `- ${p}`).join("\n")}
-You must respond in valid JSON with the key "tags" and the value is list of tags. Don't wrap the response in a markdown code.`;
+- If you can't find tags you're satisfied with respond with an empty tags array.
+${customPrompts && customPrompts.map((p) => `- ${p}`).join("\n")}`;
 }
 
 export function buildTextPrompt(
@@ -17,17 +19,14 @@ export function buildTextPrompt(
   content: string,
 ) {
   return `
-You are a bot in a read-it-later app and your responsibility is to help with automatic tagging.
-Please analyze the text between the sentences "CONTENT START HERE" and "CONTENT END HERE" and suggest relevant tags that describe its key themes, topics, and main ideas. The rules are:
-- Aim for a variety of tags, including broad categories, specific keywords, and potential sub-genres.
-- The tags language must be in ${lang}.
-- If it's a famous website you may also include a tag for the website. If the tag is not generic enough, don't include it.
-- The content can include text for cookie consent and privacy policy, ignore those while tagging.
-- Aim for 3-5 tags.
-- If there are no good tags, leave the array empty.
+You're an expert document tagger. Given an input you generate an JSON object of the following format: { "tags": ["First tag", "Another tag", ...] }
+
+Only respond in this format! Write only the JSON data and nothing else. Do not write an explanation.
+
+- If you can't find tags you're satisfied with respond with an empty tags array.
+- Write at most five tags.
+- Write your tags in ${lang}.
 ${customPrompts && customPrompts.map((p) => `- ${p}`).join("\n")}
-CONTENT START HERE
-${content}
-CONTENT END HERE
-You must respond in JSON with the key "tags" and the value is an array of string tags.`;
+
+${content}`;
 }