fix(data): add source citations for 13 tablet/watch records

[Seungpyo1007]

Summary

Upgrades uncited data/tablet/ and data/watch/ records from dataset-only
provenance (Kaggle / aitoolbuzz / GSMArena-scrape / GitHub) to
source-verified by confirming the stored specs field-by-field against
authoritative sources (Wikipedia infoboxes, manufacturer / GSMArena spec
pages) and setting verified: true. Existing dataset provenance URLs are
retained alongside the new sources. No value was invented and no citation
was fabricated.

Methodology

1. Scanned data/tablet/ and data/watch/ live for records with
   verified != true. None had empty source_urls — every record already
   carried a bulk-dataset link, so the gap was uncited, not unsourced.
   Live scope: tablet 3305 total / 3020 unverified;
   watch 418 total / 325 unverified.
2. Focused on well-documented modern flagships whose exact stored fields
   (RAM, battery, weight, OS, SoC, storage) can be confirmed against a
   dedicated Wikipedia infobox or manufacturer/GSMArena spec page.
3. Source confirms the values -> added the source URL (where not already
   present) and set verified: true.
4. Source contradicts a value -> corrected the value to match the cited
   source (never invented) and cited it.
5. No confirmable per-model source (e.g. records citing GSMArena pages that
   are rate-limited/unfetchable, phonedb entries marked "preliminary" or
   contradicting the stored RAM, or generic dataset configs whose values
   cannot be pinned to one authoritative page) -> left as-is, uncited.

Counts

Records touched: 13 (8 tablet + 5 watch)

• Newly cited-and-verified (no value change): 10

  • Tablets (7): Samsung Galaxy Tab S11, Tab S11 Ultra, Tab S10 Ultra,
    Tab S10+, Galaxy Fold, Galaxy Z Fold 6, Amazon Kindle Fire (2011).
  • Watches (3): Google Pixel Watch 4 41mm, Pixel Watch 4 45mm,
    Samsung Galaxy Watch Ultra.

• Value-corrected-with-citation: 3

  • Microsoft Surface 2 os "Windows Mobile" -> "Windows RT 8.1" (Wikipedia)
  • Samsung Galaxy Watch 7 storage_options_gb [2, 32] -> [32] (spurious 2 GB removed; Wikipedia)
  • Samsung Galaxy Watch 6 storage_options_gb [2, 16] -> [16] (spurious 2 GB removed; Wikipedia)

• Left uncited (no confirmable source in this pass): 3312
  (3012 tablet + 300 watch) — remaining bulk-dataset records not
  individually confirmed in this batch; untouched, keep existing provenance.
  Many cite GSMArena/phonedb pages that are strong follow-up candidates once
  fetchable.

Verification

• python -m app.validate -> passed.
• python integrity_check.py <data> --strict -> "integrity gate: no hard
  anomalies" (no verified-without-sources, no dup/slug issues).
• Static dump regenerated with python -m app.dump from TechEngine against
  this worktree (fresh scratch DATABASE_URL, TECHAPI_DATA_DIR -> this
  worktree data/) as the final commit; tablet/watch detail pages reflect
  the new citations and corrections. Unrelated scoring / updated_at drift
  for other categories was excluded to keep the PR scoped.

Refs #296