Reconciliation report: inferred schema vs. declared data dictionary

[amc-corey-cox]

When a data dictionary is provided alongside data files, generate a reconciliation report surfacing discrepancies between what the data shows and what the dictionary declares.

Examples of discrepancies

• Dictionary says a column is required, but data has nulls
• Dictionary says integer range, but data contains strings
• Dictionary declares coded values that don't appear in the data (or vice versa)
• Column exists in data but not in dictionary (or vice versa)

Output

• Human-readable report (could be YAML, TSV, or terminal output)
• Optionally machine-readable for downstream tooling

Scope

• Pure comparison logic — no LLM dependency
• Works with the inferred schema and the ingested data dictionary (Ingest structured data dictionary to enrich inferred schemas #192)

Depends on #192. Part of #190.