Migrate field-convert + field-convert-link onto a lifecycle driver

[HynLcc]

Tightly-coupled family migration. field-convert and field-convert-link
share the convertField endpoint and the same lifecycle, so they move onto one
new family-shaped driver.

Scope

• Runner kinds: field-convert (2 cases) + field-convert-link (2 cases)
• Cases: field-convert/10k-multi-select-to-text, field-convert/10k-text-to-formula,
  field-convert/10k-link-to-text, field-convert/10k-text-to-link

Change

• New field-convert-lifecycle.ts owns the repeated protocol: prepare(seed) →
  seedReady → measured convert+readiness → build result (twice: diagnostic
  catch + success) → finally keep-or-delete cleanup. It owns the shared
  keepFixture decision (Class D — the convert rewrites the column in place, so
  keep only when the execute DB is isolated or a reusable seed was never
  converted); the runner declares which table(s) to drop (field-convert: host;
  field-convert-link: host + foreign).
• Both runners keep only case-specific diff logic (seed-cache fixture carrying
  its own create/seed measurements, seed assertion, the measured convert +
  routing + readiness bundle, result assembly, cleanup target) and wire into the
  driver via a spec.

G1 mask additions (scripts/diff-artifacts.mjs)

These cases were never G1-diffed before; baseline A vs B surfaced
generated-field-id noise the comparator did not yet mask. All genuinely volatile
on unchanged code, none semantic:

• details.convert.sourceFieldId (→ GENERATED_ID_KEYS; sourceFieldName stays visible)
• details.convertedField.id (scoped; convertedField.name/type stay visible)
• details.verifiedSamples[].actual.id for text-to-link (scoped; the linked
  cell's actual.title stays visible and asserted)

Verification

• pnpm check: green.
• Local v1+v2 baseline A, baseline B, candidate for all 4 cases: all pass.
• G1 diff: baseline A↔B and A↔candidate pass for all 4 cases × both engines
  (with the noted mask additions, confirmed sufficient by A↔B).
• Negative battery: perturbing convertedField.type, convert.targetType,
  convert.sourceFieldName, verifiedSamples[].actual.title,
  fullScan.scannedRecords, or phases[0].name all fail the diff; the 3
  masked id fields correctly pass.
• The updated comparator still passes for the already-migrated record-reorder
  artifacts (no comparator regression).
• Candidate routing matched (feature=convertField), operation field-convert /
  field-convert-link, fullScan scannedRecords=10000.

Protected case-contract surface (cases/**, registry.ts, framework/types.ts
config, framework/artifacts.ts schema, ../teable-ee) untouched. The
scripts/diff-artifacts.mjs mask change is task-sanctioned and masks only
run-to-run-volatile generated ids.

🤖 Generated with Claude Code