fix(artifact): make comparability side-aware

[gcko]

PR checklist

• Ensure you have added or ran the appropriate tests for your PR.
• DCO signed

What type of PR is this?

Bug fix

What this PR does / why we need it:

• Classifies base and current dbt artifacts independently and exposes bounded, side-aware health through Recce's info contract.
• Carries catalog evidence through lineage and schema coverage so checks, summaries, MCP approval, and persisted results fail closed when either side is incomplete.
• Adds shared UI types and helpers that render targeted base/current warnings without treating an incomplete comparison as a schema match.

Which issue(s) this PR fixes:

Closes DRC-3303

Special notes for your reviewer:

• Companion Recce Cloud PR: https://github.com/DataRecce/recce-cloud-infra/pull/1703
• Full backend verification at this exact head: 1,761 passed, 5 skipped.
• Frontend verification at this exact head: 4,305 passed, 5 skipped; lint and type-check pass.
• dbt 1.6 and 1.7 tox suites: 1,440 passed, 21 skipped in each environment.
• dbt 1.8, 1.9, and latest tox environments are blocked before tests by local TLS certificate verification while fetching the external dbt-core-experimental-parser GitHub wheel. No test failure was observed in those environments.

Does this PR introduce a user-facing change?:

Yes. Recce now identifies which artifact side is incomplete, shows side-specific warnings, and prevents unsafe schema approval or match reporting.

[codecov]

Codecov Report

❌ Patch coverage is 98.71345% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
recce/run.py	89.65%	6 Missing ⚠️
recce/artifact_health.py	95.76%	5 Missing ⚠️

Files with missing lines	Coverage Δ
recce/adapter/dbt_adapter/__init__.py	79.65% <100.00%> (+0.07%)	⬆️
recce/mcp_server.py	90.98% <100.00%> (-0.05%)	⬇️
recce/models/lineage.py	100.00% <100.00%> (ø)
recce/models/types.py	97.72% <100.00%> (+0.27%)	⬆️
recce/summary.py	80.79% <100.00%> (+12.62%)	⬆️
recce/tasks/schema.py	95.91% <100.00%> (+49.40%)	⬆️
recce/util/info_emitter.py	95.23% <ø> (ø)
tests/adapter/dbt_adapter/test_dbt_adapter.py	100.00% <100.00%> (ø)
tests/dbt_flags.py	100.00% <100.00%> (ø)
tests/tasks/test_schema.py	100.00% <100.00%> (ø)
... and 10 more

... and 3 files with indirect coverage changes

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