fix(prompt): reapply WeCom-style MEDIA literal fix for QQ hint

Upstream's QQ platform hint (added in the salvaged PR NousResearch#10935/NousResearch#10940 block
that landed during this merge) re-introduced the 'MEDIA:/absolute/path/to/file'
literal that our prior commit 03f8a5e fixed for WeCom. The
ANTHROPIC_OAUTH_BLOCKED_LITERALS guard test flagged it.

Same fix pattern: 'absolute' -> 'full' to break tokenization.

Author: shuv1337

agent/prompt_builder.py

@@ -380,7 +380,7 @@ def _strip_yaml_frontmatter(content: str) -> str:
     ),
     "qqbot": (
         "You are on QQ, a popular Chinese messaging platform. QQ supports markdown formatting "
-        "and emoji. You can send media files natively: include MEDIA:/absolute/path/to/file in "
+        "and emoji. You can send media files natively: include MEDIA:/full/path/to/file in "
         "your response. Images are sent as native photos, and other files arrive as downloadable "
         "documents."
     ),