refactor: decompose func_metadata() into smaller focused helpers #1656

Job	Run time
checks / readme-snippets	13s
checks / pre-commit	37s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.10, locked, ubuntu-latest)	50s
checks / test (3.12, locked, ubuntu-latest)	53s
checks / test (3.11, lowest-direct, ubuntu-latest)	58s
checks / test (3.10, locked, windows-latest)	2m 24s
checks / test (3.10, lowest-direct, windows-latest)	2m 28s
checks / test (3.11, locked, ubuntu-latest)	49s
checks / test (3.13, locked, ubuntu-latest)	48s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 12s
checks / test (3.13, locked, windows-latest)	2m 3s
checks / test (3.11, locked, windows-latest)	2m 22s
checks / test (3.14, locked, windows-latest)	3m 12s
checks / test (3.12, lowest-direct, windows-latest)	3m 28s
checks / test (3.11, lowest-direct, windows-latest)	2m 30s
checks / test (3.13, lowest-direct, windows-latest)	2m 34s
checks / test (3.13, lowest-direct, ubuntu-latest)	51s
checks / test (3.12, lowest-direct, ubuntu-latest)	57s
checks / test (3.14, locked, ubuntu-latest)	2m 17s
checks / test (3.12, locked, windows-latest)	3m 3s
checks / test (3.14, lowest-direct, windows-latest)	2m 13s
all-green	4s
	37m 48s

Provide feedback