Change JQ to process newline-delimited JSON

[tho]

Update JQ filter to handle newline-delimited JSON (NDJSON).

Fixes #226.

Implementation Notes

• Used decoder's More() method for cleaner iteration over JSON stream
• Preserved existing code style with short variable names
• Preserved error handling approach with early returns
• Preserves interface{} usage instead of any
• No return value checks for fmt.Fprintln
• Direct return of external package errors without wrapping
• Wrote individual tests instead of table driven tests

Example

Analyzes logs to count and display frequency of different log levels from newline-delimited JSON input.

cat log.json | ./goscript.sh -c 'script.Stdin().JQ(".level").Freq().Stdout()'
3 "INFO"
2 "WARN"
1 "ERROR"

[bitfield]

@tho great work! I've made a few minor tweaks for house style and so on—are you okay with these?

[tho]

lgtm. Thanks for the quick review!