data(brand): real descriptions for recognizable brands

[Seungpyo1007]

Summary

Replace the generic placeholder brand descriptions ("Phone brand observed in the GSMArena mobile devices dataset…") with real, factual EN + KO descriptions for 53 recognizable brands (Sony Ericsson, Palm, Vodafone, Orange, O2, Casio, Dell, HP, Amazon, T-Mobile, Bosch, Haier, Sagem, Sonim, Telit, Thuraya, Benefon, Qtek, E-TEN, MiTAC, Karbonn, Intex, verykool, Yezz, …).

Changes

• 53 data/brand/**/*.json: real description_en + description_ko (replacing the placeholder + filling the missing Korean field).
• 53 matching site/public/v1/brands/<slug>/index.json dump details refreshed (descriptions are verbatim passthrough, so the dump matches a full regenerate).
• 7 genuinely-obscure brands (Chea, XCute, MWg, Parla, NIU, WND, …) intentionally keep their provenance placeholder — no fabricated facts.
• Descriptions are conservative (region/segment) for unaudited brands (verified: false); audit can refine later.

Verification

• python -m app.validate PASS
• python TechEngine/integrity_check.py data --strict PASS
• git diff --check origin/main...HEAD PASS
• Local site build skipped (isolated worktree has no node_modules); change is build-safe description text and the TechEngine homepage validation builds the site.

Closes #1