jsonsample emits the same flat path format as jsonrawpaths but with
actual JSON values at leaf nodes and compact JSON samples at type intro
lines (e.g., {Root:{"name":"pikachu","id":25,...}}). Output is auto-
coalesced: types deduplicated by key set, one sample per primitive type.
Updated coalescer to handle TypeName:Sample format in type intros,
using first { instead of last { for parsing (handles nested JSON braces).
Sample output is valid input for jsoncoalesce (idempotent round-trip).
