Use hash routing on invite URLs.

Dependencies

• [2] 46PUXHTY Implement project invitations.
• [3] X3ES7NUA Fine. I'll use ormolu. At least it doesn't break the code.
• [4] 6L5BK5EH Use generic SMTP rather than Sendmail-specific mail client.
• [*] PBD7LZYQ Postgres & auth are beginning to function.

Change contents

• replacement in server/Aftok/Snaplet/Projects.hs at line 225
  [2.19149]→[2.19149:19177](∅→∅)
  − <> zaddr,
  [2.19149]

  [2.19177]
  + <> zaddr

  + <> "#signup",