fix: Beschreibung generieren gibt jetzt reinen Fließtext aus

Neuer raw_text Parameter in call_claude() umgeht den JSON-System-Prompt.
Haiku gibt direkt lesbaren Text zurück statt JSON-Objekte.
Gesamtes JSON-Parsing (_json_to_text, Markdown-Strip) entfernt.

src/agents/claude_client.py

@@ -43,7 +43,7 @@ def _sanitize_mdash(text: str) -> str:
     """Entfernt Gedankenstriche aus LLM-Output (KI-Indikator)."""
     return text.replace("\u2014", ", ").replace("\u2013", ", ")
 
-async def call_claude(prompt: str, tools: str | None = "WebSearch,WebFetch", model: str | None = None) -> tuple[str, ClaudeUsage]:
+async def call_claude(prompt: str, tools: str | None = "WebSearch,WebFetch", model: str | None = None, raw_text: bool = False) -> tuple[str, ClaudeUsage]:
     """Ruft Claude CLI auf. Gibt (result_text, usage) zurück.
 
     Prompt wird via stdin uebergeben um OS ARG_MAX Limits zu vermeiden.
@@ -60,11 +60,12 @@ async def call_claude(prompt: str, tools: str | None = "WebSearch,WebFetch", mod
         cmd.extend(["--allowedTools", tools])
     else:
         cmd.extend(["--max-turns", "1", "--allowedTools", ""])
-        cmd.extend(["--append-system-prompt",
-            "CRITICAL: You are a JSON-only output agent. "
-            "Output EXCLUSIVELY a single valid JSON object. "
-            "No explanatory text, no markdown fences, no continuation of previous responses. "
-            "Start your response with { and end with }."])
+        if not raw_text:
+            cmd.extend(["--append-system-prompt",
+                "CRITICAL: You are a JSON-only output agent. "
+                "Output EXCLUSIVELY a single valid JSON object. "
+                "No explanatory text, no markdown fences, no continuation of previous responses. "
+                "Start your response with { and end with }."])
 
     process = await asyncio.create_subprocess_exec(
         *cmd, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE,