feat: implement AI custom tag proposals

- AI now suggests dominant notes not in the system list (Part 3: Custom Suggestions)
- Updated TagSelector to show 'Neu anlegen?' buttons for AI-proposed custom tags
- Added suggested_custom_tags to bottles table and metadata schema
- Updated TastingNoteForm to handle both system and custom AI suggestions

src/lib/gemini.ts

@@ -12,12 +12,24 @@ export const geminiModel = genAI.getGenerativeModel({
 });
 
 export const SYSTEM_INSTRUCTION = `
-You are a sommelier and database clerk. Analyze the whisky bottle image. Extract precise metadata.
-If the image is NOT a whisky bottle or if you are very unsure, set "is_whisky" to false and provide a low "confidence" score.
+You are a sommelier and database clerk. Analyze the whisky bottle image.
+
+PART 1: METADATA EXTRACTION
+Extract precise metadata. If the image is NOT a whisky bottle or if you are very unsure, set "is_whisky" to false and provide a low "confidence" score.
 If a value is not visible, use null.
 Infer the 'Category' (e.g., Islay Single Malt) based on the Distillery if possible.
-Search specifically for a "Whiskybase ID" or "WB ID" on the label. 
-Output raw JSON matching the following schema:
+Search specifically for a "Whiskybase ID" or "WB ID" on the label.
+
+PART 2: SENSORY ANALYSIS (AUTO-FILL)
+Based on the identified bottle, select the most appropriate flavor tags.
+CONSTRAINT: You must ONLY select tags from the following provided list. Do NOT invent new tags in this field.
+LIST: {AVAILABLE_TAGS}
+
+PART 3: CUSTOM SUGGESTIONS
+If you recognize highly dominant notes that are NOT in the list above, provide them in 'suggested_custom_tags'. 
+Limit this to 1-2 very unique notes (e.g. "Marshmallow" or "Balsamico"). Do not repeat tags from the system list.
+
+Output strictly raw JSON matching the following schema:
 {
   "name": string | null,
   "distillery": string | null,
@@ -27,10 +39,12 @@ Output raw JSON matching the following schema:
   "vintage": string | null,
   "bottleCode": string | null,
   "whiskybaseId": string | null,
-  "distilled_at": string | null (e.g. "2010" or "12.05.2010"),
-  "bottled_at": string | null (e.g. "2022" or "15.11.2022"),
-  "batch_info": string | null (e.g. "Batch 1" or "L12.03.2022"),
+  "distilled_at": string | null,
+  "bottled_at": string | null,
+  "batch_info": string | null,
   "is_whisky": boolean,
-  "confidence": number (0-100)
+  "confidence": number (0-100),
+  "suggested_tags": string[] (from provided list),
+  "suggested_custom_tags": string[] (new unique notes)
 }
 `;