cowork: scan fails loudly when no config files load (silent-green guard)

[Coding-Dev-Tools]

Fixes a silent-failure trap in configdrift scan: if every configured environment directory was missing or empty, the CLI printed warnings and exited 0 reporting 'no drift' — a false green for CI gating.

Changes:

• Exit 1 when zero config files could be loaded across all environment directories.
• Exit 1 when the baseline environment loaded no config keys (diffing against an empty baseline would flag every key as drift).
• 5 regression tests (TestScanEmptyGuards); suite: 148 passed; ruff clean.

[github-actions]

🤖 Automated Code Review

✅ Ruff Lint — No issues

⚠️ Ruff Format — Formatting needed

unformatted: File would be reformatted
   --> src/configdrift/cli.py:18:19
    |
17  |
    -     warnings.warn(
    -         "revenueholdings-license not installed; license checks skipped", stacklevel=2
    -     )
18  +     warnings.warn("revenueholdings-license not installed; license checks skipped", stacklevel=2)
19  |
--------------------------------------------------------------------------------
68  |     global _require_license_strict
    -     _require_license_strict = require_license_flag or bool(
    -         os.environ.get("REVENUEHOLDINGS_REQUIRE_LICENSE")
    -     )
69  +     _require_license_strict = require_license_flag or bool(os.environ.get("REVENUEHOLDINGS_REQUIRE_LICENSE"))
70  |     if _require_license_strict:
71  |         try:
72  |             from revenueholdings_license import require_license as _rl
73  +
74  |             _rl("configdrift")
--------------------------------------------------------------------------------
96  | _DEFAULT_STRICT = False
    - _FILES_ARG = typer.Argument(
    -     ..., help="Config files to compare (2+ files; first file is baseline)."
    - )
97  + _FILES_ARG = typer.Argument(..., help="Config files to compare (2+ files; first file is baseline).")
98  | _BASELINE_OPT = typer.Option(
--------------------------------------------------------------------------------
115 | )
    - _STRICT_OPT = typer.Option(

✅ Secret Detection — Clean

✅ Large Files — Within limits

📊 Diff Stats — 4 file(s) changed

 src/configdrift/cli.py  | 18 +++++++++++++++
 src/configdrift/diff.py | 15 ++++++++++++-
 tests/test_cli.py       | 58 +++++++++++++++++++++++++++++++++++++++++++++++++
 tests/test_diff.py      | 34 +++++++++++++++++++++++++++++
 4 files changed, 124 insertions(+), 1 deletion(-)

---

Verdict: ⚠️ Warnings — Lint/format issues found. Recommend fixing before merge.

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