Make AnyFrame.cast verify schemas by default

[Copilot]

The no-argument cast() overload currently bypasses schema verification, allowing mismatches to fail later during column access. Make checked casting the default while retaining an explicit escape hatch for trusted unchecked casts.

• Casting API

  • cast<T>() now uses schema verification by default.
  • Added castUnsafe<T>() for unchecked DataFrame and DataRow casts.
  • Preserved verify = false and existing JVM signatures.

• Internal usage

  • Updated generic/internal casts to call castUnsafe() explicitly.
  • Regenerated processed core sources and updated cast documentation.

• Regression coverage

  • Default casts now assert on schema mismatches.
  • Unchecked casts and verify = false remain supported.

val raw = dataFrameOf("name" to columnOf("Ada"))

raw.cast<Person>()                 // Fails fast if Person's schema differs
raw.cast<Person>(verify = false)   // Skips verification
raw.castUnsafe<Person>()           // Explicit unchecked cast

• Fixes Make AnyFrame.cast actually check schema by default #1932