Fix importing real Apple Mail forwards

[kirahowe]

Summary

• recognize Apple Mail forwards whose marker and original headers are separate sibling elements
• exclude forwarding headers such as Reply-To from the imported newsletter body
• accept Apple Mail's undashed plain-text marker and leading separator line
• bump the extraction version to 3 so stored version-2 newsletters can be reprocessed
• ignore local inbox_*.eml uploads so real messages cannot be committed accidentally

The regression markup is redacted and structurally derived from a real failing .eml; the source message itself is not included.

Verification

• the real uploaded .eml is detected as an Apple Mail forward, uses the original subject and sender, strips forwarding chrome, and produces a nonempty body
• 241 tests, 1,439 assertions, 0 failures
• clj-kondo clean
• cljfmt clean