feat(license): registration + 1-year licenses + tier scaffolding

A complete offline licensing layer (no internet at any step):

Core
- src/license/ — schema (License, Tier, FeatureFlag), HMAC crypto,
  JSON storage, LicenseManager singleton with activate/renew/
  deactivate/issue_trial. Tier-scaffolded so future SKUs can carve
  per-tool feature sets without consumer-code edits.
- scripts/generate_license.py — creator-only key generator. Mints a
  DTLIC1: blob the buyer pastes into the activation page.

GUI
- New activation form component (src/gui/components/activation.py).
- hide_streamlit_chrome() now inline-renders the activation form when
  no valid license is present (every page short-circuits to the form
  until activated).
- Sidebar shows tier + days remaining; renewal warning under 30 days.
- New pages/_Activate.py for revisiting the form after activation.

CLI
- src/license_cli.py — activate / renew / status / trial / deactivate
  commands. Exempt from the guard.
- src/cli_license_guard.py — drop-in guard call added to every tool
  CLI's main(). Lets --help through; respects DATATOOLS_DEV_MODE.

i18n
- New activation.* and license.* keys in en.json + es.json
  (page title, form labels, status badges, renewal warnings, error
  messages). Pack parity test stays green.

Test infrastructure
- tests/conftest.py autouse fixture sets DATATOOLS_DEV_MODE=1 so the
  existing 1916 tests continue to pass.
- isolated_license_path / activated_license_manager /
  unactivated_license_manager fixtures for tests that want to drive
  the real check.

Tests (+79)
- tests/test_license.py (40): schema, crypto roundtrip, blob
  encode/decode, tier→feature mapping, activation flow, name/email
  mismatch rejection, tamper detection, expiration, renewal,
  dev-mode bypass.
- tests/test_license_cli.py (26): every license_cli command +
  subprocess tests confirming every tool CLI refuses to run without
  a license, --help always works, DEV_MODE bypasses.
- tests/gui/test_activation.py (13): gate blocks without license,
  passes with trial, activation form submission unlocks the gate,
  sidebar status, renewal warning, i18n.

Total: 1916 → 1995 tests. All pass under the strict warning filter.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/cli.py

@@ -499,6 +499,8 @@ def _write_match_groups(result, original_df, path: Path) -> None:
 # ---------------------------------------------------------------------------
 
 def main():
+    from src.cli_license_guard import guard
+    guard()
     app()