feat: api accepts 'vllm' as a first-class value

'openai' reads as the cloud company — an operator running
self-hosted vLLM should be able to write what they mean. The new
value speaks the identical OpenAI wire (a guard test asserts the
emitted request stays byte-identical to api: openai, so the alias
can never drift into a dialect) but yields vLLM-specific error
hints (vllm serve, port 8000) instead of generic OpenAI prose.
Manifest + docs name the value in DE and EN.

Signed-off-by: flemming-it <sf@flemming.it>

module.yaml

@@ -35,13 +35,20 @@ inputs:
     type: text
     description:
       en: |
-        Optional wire format: "ollama" (default), "openai"
-        (Chat Completions — OpenAI, vLLM, compatible servers),
-        or "anthropic" (Messages API). Empty = ollama.
+        Optional wire format: "ollama" (default), "vllm"
+        (self-hosted vLLM), "openai" (OpenAI or other
+        OpenAI-compatible servers such as LM Studio), or
+        "anthropic" (Messages API). vllm and openai speak the
+        same wire; the separate value exists so you can write
+        what you mean and get vLLM-specific hints. Empty = ollama.
       de: |
-        Optionales Wire-Format: "ollama" (Default), "openai"
-        (Chat Completions — OpenAI, vLLM, kompatible Server)
-        oder "anthropic" (Messages API). Leer = ollama.
+        Optionales Wire-Format: "ollama" (Default), "vllm"
+        (selbst gehostetes vLLM), "openai" (OpenAI oder andere
+        OpenAI-kompatible Server wie LM Studio) oder "anthropic"
+        (Messages API). vllm und openai sprechen dieselbe Wire;
+        der eigene Wert existiert, damit Du schreibst, was Du
+        meinst, und vLLM-spezifische Hinweise bekommst.
+        Leer = ollama.
   model:
     type: text
     description: