brain-gardener#5: the audit's unsourced check was flagging 59 raw
claudewatcher session dumps as high-severity hallucination risk,
because it can't distinguish a first-party observation (a session
transcript) from an external claim needing citation.
Adds WriteNoteOptions.SourceType, emitted as source_type: <value> in
the wing/hall frontmatter route. claudeSink (the claudewatcher sink)
now always sets source_type: internal on the notes it writes.
