Translate ORA-02290 to ActiveRecord::CheckViolation

[yahonda]

Summary

• Oracle raises ORA-02290 ("check constraint (…) violated") when an INSERT or UPDATE produces a row that fails a CHECK constraint. oracle-enhanced's translate_exception (oracle_enhanced_adapter.rb:1433-1452) had no entry for code 2290, so the error fell through to AbstractAdapter#translate_exception and surfaced as a generic ActiveRecord::StatementInvalid. Applications catching constraint violations could not distinguish a check failure from any other statement error.
• Map ORA-02290 to ActiveRecord::CheckViolation alongside the existing constraint-violation mappings:
  • ORA-01400 → NotNullViolation
  • ORA-02290 → CheckViolation (this PR)
  • ORA-02291 / ORA-02292 → InvalidForeignKey
  • ORA-12899 → ValueTooLong
• oracle-enhanced has supported add_check_constraint / t.check_constraint since Wire up CHECK constraint DSL: add_check_constraint, t.check_constraint, dump round-trip #2717; the missing exception mapping was the remaining gap on the CHECK-constraint surface. With this PR ActiveRecord::Base.connection.execute (and AR's create / update paths) emit the AR-portable CheckViolation for check-constraint violations on Oracle, matching the PostgreSQL / MySQL / SQLite3 contract.
• Adds a direct integration assertion in the existing describe "check constraints" block of spec/active_record/connection_adapters/oracle_enhanced/schema_statements_spec.rb: create a check constraint on test_products, attempt an INSERT that violates it, expect ActiveRecord::CheckViolation with a message matching /ORA-02290/. The assertion fails against the pre-change case (which routes 2290 to StatementInvalid via super), confirming the regression-detection power.
• No new public surface, no behavior change for non-2290 errors. Surfaced during a Rails-side follow-up audit prompted by Query command for read-only database queries rails/rails#57156 (see the survey in conversation; this is the one clean gap that emerged).

Test plan

• bundle exec rspec spec/active_record/connection_adapters/oracle_enhanced/schema_statements_spec.rb — 205 examples, 0 failures, 1 pending (no regression in the surrounding schema_statements_spec.rb, including the existing check constraints and foreign keys integration tests). Oracle Free 23.26 / FREEPDB1.
• Re-ran the same single example against the pre-change case for negative control — fails with expected ActiveRecord::CheckViolation, got #<ActiveRecord::StatementInvalid …ORA-02290…>, confirming the assertion exercises the new branch.
• bundle exec rubocop . — 104 files, no offenses.