Pre-release review findings: dead code, undefined display bugs, missing driver tests, doc gaps

[anandgupta42]

Context

During pre-release validation for v0.5.15, a 5-persona review team identified several issues that should be addressed before release:

Issues

Code fixes (pre-release)

1. Duplicate altimate_change end markers in prompt.ts at lines 812 and 962 — confuses Marker Guard CI
2. password: "secret" in test fixtures — 3 instances in feature-discovery-e2e.test.ts inconsistent with cleanup in connections.test.ts
3. Dead code in classifySkillTrigger() — returns "llm_selected" for unknown triggers instead of "unknown", making the "unknown" variant dead code
4. Unused "schema_not_indexed" type in feature_suggestion telemetry event union — declared but never used

Undefined display bugs

5. sql-translate.ts — source_dialect/target_dialect without null guards
6. dbt-manifest.ts — model.name, source.source_name, source.name without null guards; result.error not propagated to metadata
7. dbt-lineage.ts — model_name, confidence without null guards
8. altimate-core-column-lineage.ts / altimate-core-track-lineage.ts — edge.source/edge.target without null guards

Missing test coverage

9. No unit tests for driver changes — DuckDB retry logic, MongoDB pipeline blocking, PostgreSQL/Redshift password validation, registry unsupported DB hints

Documentation gaps

10. DuckDB concurrent access retry behavior undocumented
11. MongoDB blocked operators ($out, $merge, $function, $accumulator) undocumented
12. Known-unsupported databases (ClickHouse, Cassandra, CockroachDB, TimescaleDB) undocumented