* fix(internal-runtime-context): wrap prompt-preface runtime context body in delimiters
When buildRuntimeContextMessageContent constructs the hidden
runtime context prompt block, the body (which may contain
sensitive metadata like relevant-memories, sender info, and
conversation metadata) was not wrapped in the standard
INTERNAL_RUNTIME_CONTEXT_BEGIN/END delimiters. If the model
echoed this context back in its reply, stripInternalRuntimeContext
could only remove the header and notice lines — the sensitive
body leaked through to user-visible surfaces like Feishu
streaming cards.
Wrap the runtime context body in BEGIN/END delimiters so the
existing stripInternalRuntimeContext (which handles delimited
blocks first) can fully remove the entire block.
Closes#92589
* chore: retrigger CI for proof check
* chore: retrigger CI with corrected proof format
* chore: retrigger CI with corrected proof field format
21aa8faf8a