Recruiting briefs with receipts — every claim cites a resume line — step 5 of 8

The audit needs to follow each claim's receipt into the resume — without crashing when the receipt points at a line that doesn't exist (claim three cites L7; this resume stops at L2).

Fill in the lookup so a real line comes back for good receipts and None comes back for bad ones — no KeyError, no try/except.

Expected output:

Three years in benefits: SOURCED
Ran open enrollment at scale: SOURCED
Expert in self-funded plans: UNRECEIPTED