backend: replace LAST_FULL_PROMPT/LAST_CAT_INTERACTION with unified PROMPT_HISTORY deque

- globals.py: add collections.deque(maxlen=10) PROMPT_HISTORY with _prompt_id_counter
- globals.py: add legacy accessor functions _get_last_fallback_prompt() and _get_last_cat_interaction()
- bot.py: append to PROMPT_HISTORY instead of setting LAST_CAT_INTERACTION, remove 500-char truncation, add guild/channel/model fields
- image_handling.py: same pattern for Cat media responses
- llm.py: append fallback prompts to PROMPT_HISTORY with response filled after LLM reply
- routes/core.py: new GET /prompts and GET /prompts/{id} endpoints, legacy /prompt and /prompt/cat use accessor functions

bot/routes/core.py

@@ -31,18 +31,45 @@ def get_logs():
 
 @router.get("/prompt")
 def get_last_prompt():
-    return {"prompt": globals.LAST_FULL_PROMPT or "No prompt has been issued yet."}
+    """Legacy endpoint: returns the most recent fallback prompt (backward compat)."""
+    prompt_text = globals._get_last_fallback_prompt()
+    return {"prompt": prompt_text or "No prompt has been issued yet."}
 
 
 @router.get("/prompt/cat")
 def get_last_cat_prompt():
-    """Get the last Cheshire Cat interaction (full prompt + response) for Web UI."""
-    interaction = globals.LAST_CAT_INTERACTION
+    """Legacy endpoint: returns the most recent Cat interaction (backward compat)."""
+    interaction = globals._get_last_cat_interaction()
     if not interaction.get("full_prompt"):
-        return {"full_prompt": "No Cheshire Cat interaction has occurred yet.", "response": "", "user": "", "mood": "", "timestamp": ""}
+        return {"full_prompt": "No Cheshire Cat interaction has occurred yet.",
+                "response": "", "user": "", "mood": "", "timestamp": ""}
     return interaction
 
 
+@router.get("/prompts")
+def get_prompt_history(source: str = None):
+    """
+    Return the unified prompt history.
+    Optional query param ?source=cat or ?source=fallback to filter.
+    """
+    history = list(globals.PROMPT_HISTORY)
+    if source and source in ("cat", "fallback"):
+        history = [e for e in history if e.get("source") == source]
+    return {"history": history}
+
+
+@router.get("/prompts/{prompt_id}")
+def get_prompt_by_id(prompt_id: int):
+    """Return a single prompt history entry by ID."""
+    for entry in globals.PROMPT_HISTORY:
+        if entry.get("id") == prompt_id:
+            return entry
+    return JSONResponse(
+        status_code=404,
+        content={"status": "error", "message": f"Prompt #{prompt_id} not found"}
+    )
+
+
 @router.get("/status")
 def status():
     # Get per-server mood summary