fix: stop S7632 flagging NOSONAR mentioned in prose comments

SonarCloud's python:S7632 parses the literal ``# NOSONAR`` token wherever it
appears — including inside explanatory comments that *quote* the directive —
and treats the following text as a malformed suppression. The actual bare
``# NOSONAR`` suppression lines are fine; the flagged lines were the prose
comments describing them. Reword those comments to drop the inner ``#`` so the
analyzer no longer sees a directive.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/embedding/gateway_client.py

@@ -122,8 +122,8 @@ class GatewayProvider(OpenAIProvider):
         # AsyncOpenAI rejects an empty key; use a non-secret placeholder when
         # the gateway is unauthenticated. When a token provider is configured,
         # the real Bearer is set on the client before each request. The bare
-        # ``# NOSONAR`` silences the hard-coded-credential hotspot — this is a
-        # public placeholder string, not a secret.
+        # suppression marker below silences the hard-coded-credential hotspot —
+        # this is a public placeholder string, not a secret.
         super().__init__(
             api_key=_UNAUTHENTICATED_PLACEHOLDER,  # NOSONAR
             base_url=base_url,