fix: update drifted source citations to match current upstream
Verified all 17 file:line citations against elixir-lang/elixir HEAD.
Fixed 10 citations where line numbers had shifted due to upstream changes:
- patterns/genserver.md: agent.ex:246 → 279 (start_link spec)
- patterns/process-design.md: task.ex:282 → 327 (child_spec)
- smells/anti-patterns.md: registry_test.exs:28 → 29, gen_server_test.exs:166 → 164,
test_helper.exs:98 → 99
- smells/common-mistakes.md: registry_test.exs:28 → 29, callbacks.ex:423 → 433,
task_test.exs:297,305,315,330 → 300,308,316,327,
supervisor_test.exs:278 → 289, callbacks.ex:277 → 520
Rodin
40f024b477