Render mighost 0.5 ghost classification and add RBW_FORCE

[amberpixels]

What

Teaches db:migrate:status to read the ghost classification mighost 0.5 provides, fixes a branch-badge leak that classification made reachable, and adds an RBW_FORCE escape hatch for formatting auto-detection.

Ghost classification

Ghost data now comes from Mighost::API.orphaned_migrations (one call, indexed by version) instead of per-version find_or_recover_snapshot. Each ghost row carries the most informative badge available, by precedence:

1. ≡ <version> - the migration was re-timestamped and lives on under another applied version. The row also gets a calmer 🪦 status instead of 👻, since it's stale bookkeeping rather than a lost migration.
2. ⌥ <branch> / ⌥ₜ<branch> - unchanged branch attribution.
3. ✂ deleted in:<sha> - the commit that removed the file, when no branch still holds it.

Because detection goes through mighost's orphan detector, db:migrate:status now honors dismissals and hide_superseded for the first time: a suppressed ghost renders as plain NO FILE. Versions the detector lists without a stored snapshot still fall back to live git/worktree recovery, so fresh clones keep working with zero setup.

Branch badge leak fix

The ghost branch tag was assigned inside a conditional and never reset per row, so a branchless ghost inherited the previous ghost's badge. Unreachable while mighost always guessed a branch; mighost 0.5 makes nil branches the normal case. The tag is now built fresh per row, and a regression spec renders two ghost rows to prove the second stays clean.

RBW_FORCE

Railbow.plain? returns true under CLAUDECODE, NO_COLOR, CI, or non-tty output, with no way back in (RBW_PLAIN=0 is just falsy). RBW_FORCE=1 now overrides all auto-detection - useful for capturing formatted output to a file or letting an agent inspect the real rendering. An explicit RBW_PLAIN=1 still wins. Documented in RBW_HELP and the README env table.

Testing

• Railbow.plain? truth table across RBW_PLAIN / RBW_FORCE / NO_COLOR / CLAUDECODE / CI / tty.
• Tag precedence unit specs (superseded > branch > deleted > none).
• Leak regression: two ghost rows rendered in order, second (branchless) carries no badge - fails on main.
• Fallback path: version listed without a filename triggers live recovery; version absent from detection does not and renders plain NO FILE.

just lint and bundle exec rspec (323 examples) pass.