feat(verify): migrate verification layer into TechEngine

app/verify/__init__.py

@@ -0,0 +1,18 @@
+"""TechAPI data *verification* layer (§ existence/trust, sits above structural validation).
+
+``app.validate`` answers "is this record well-formed?". ``app.verify`` answers
+"does this record describe a real, actually-existing device/part — confidently
+enough to mark it ``verified``?".
+
+It is a separate, additive layer: the structural validator (``app/validate.py``)
+stays the fast CI gate and is never rewritten. Verification is tiered:
+
+* Tier 0 — offline deterministic plausibility score over the whole dataset
+  (``offline``/``signals``/``hosts``); bands records green/yellow/red.
+* Tier 1 — ``source_urls`` HTTP liveness (``http_check``).
+* Tier 2 — external cross-reference under an exact-heading rule (``crossref``).
+* Tier 3 — hybrid escalation + safe ``verified:true`` write-back (``promote``).
+
+Decisions are recorded append-only in ``data/_verify/ledger.jsonl`` so runs are
+incremental and resumable.
+"""

app/verify/__main__.py

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+"""``python -m app.verify`` entry point."""
+
+import sys
+
+from .cli import main
+
+if __name__ == "__main__":
+    sys.exit(main())