feat(contributor-growth): ask the maintainer for the addresses people post from

[potiuk]

Summary

Contributors often post to the project list from an address they never
commit with (a work address), or one the list rewrites to
"Name via ". The community signals then attribute nothing to them,
and the brief reads as if they never posted.

community-signals.md now has an Ask the maintainer for addresses
step:

• it reads maintainer-confirmed mailing_list addresses from
  contributor-identities.md in the personal layer first;
• for anyone still without a confirmed address with posts in the window,
  it proposes possible matches in both directions: a display-name search,
  and best guesses over every sender in the window (name variants,
  initials, address local parts, company domain), graded strong /
  plausible / weak;
• the maintainer accepts or rejects each one, and every row defaults to
  reject; nothing is attributed from an unaccepted address;
• accepted ones are recorded in the identity file (new mailing_list
  channel, grade: maintainer-confirmed) after the maintainer confirms
  the diff, so later runs ask only about people who still have none.

candidate-screen Step 3 runs it once for everyone after measuring, and
the identity-file format in identity-map/sources.md shows the new
channel.

Type of change

• Behaviour change (skill)

Test plan

• Used end to end: mappings proposed and confirmed, recorded in the
  personal layer, list activity collected for them
• prek run --all-files passes

Generated-by: Claude Opus 5

🤖 Generated with Claude Code