test(router): route-iterating done-bar coverage guard (#249)

Walks the live Fiber route stack and asserts every registered route is either
mapped to a covering integration test (routeTestMap) or in an explicit
exemptions list with justification — reds CI when a NEW route is added without
a test (the structural defense against the login-outage / silent-untested-route /
Team-buyable classes). TestDoneBar_TestMapPointsAtRealTests (go/ast scan) closes
the map-rot loophole. Pure source-scan, no DB, runs in -short. Mirrors the
mcp/cli/provisioner registry guards.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mastermanas805