The fork protection logic incorrectly treated all repos where
origin != steveyegge/beads as forks, including user's own projects
that just use beads as a tool.
Changes:
- Add isForkOfBeads() that scans ALL remotes for steveyegge/beads
- Only apply protection when a beads-related remote exists
- Add git config opt-out: `git config beads.fork-protection false`
(per-clone, never tracked, matches beads.role pattern)
Test coverage for 8 scenarios plus edge cases for config values.
f3f713d77a