v6.3.1 — crawlforge login works on Linux

Fixed

• crawlforge login crashed on Linux with ERR_MODULE_NOT_FOUND. src/cli/commands/login.js imported ../../core/authManager.js while the file is AuthManager.js. macOS and Windows filesystems are case-insensitive and resolve that; Linux and Docker do not, so the command died at import for every Linux user from 6.1.0, where it shipped. Every other reference in the tree already used the correct case — this was the only outlier, and a sweep of all 363 tracked sources found no others.

CI had been reporting this since 6.1.0 and it was read past three times: the test file failed at import, so the runner showed one failing test at cliLogin.test.js:1:1 with no assertion message, which reads like an environmental blip rather than a broken command. A new tests/unit/importCaseExactness.test.js compares every relative import against git ls-files rather than the disk, because a developer on a case-insensitive filesystem cannot reproduce this at runtime.

Verified on Linux: node:22-alpine — the Node version CI pins — runs the login suite 10/10. Full suite: 163 files, 2139 tests, 0 failures. CI on main is green for the first time since 6.1.0.

No API or output changes.