fix(verify): shallow-safe changed-record detection (unblocks Tiers 1-3)

[Seungpyo1007]

CI fetches main --depth=1; the three-dot origin/main...HEAD diff needs a merge-base that a shallow main lacks, so --changed/pr always saw 0 changed records and skipped the network tiers. Switch to a direct git diff origin/main HEAD (only needs both tips). Refs #1

[Seungpyo1007]

🔎 Data verification — Tier 0 (offline existence/trust)

Scored by app.verify; posted by TechEngineBot. Informational only — the structural gate (app.validate) is separate and authoritative for merge.

Changed records in this PR

No records scored.

Full-dataset baseline

101954 record(s) scored.

Category	Total	🟢 Green	🟡 Yellow	🔴 Red	Green %
brand	189	10	179	0	5.3%
soc	2104	123	680	1301	5.8%
smartphone	90118	8453	80547	1118	9.4%
tablet	3048	174	2846	28	5.7%
watch	378	11	357	10	2.9%
pda	110	27	77	6	24.5%
gpu	2030	245	1785	0	12.1%
cpu	3977	976	3001	0	24.5%
All	101954	10019	89472	2463	9.8%

_{green = authoritative source + complete + consistent · yellow = plausible, needs confirmation · red = sparse/weak source or a hard contradiction. Promotion to verified runs in the scheduled verify-network workflow.}