Validate cube dimension reachability during deployment

[saisharan0103]

Issue #2249

Root cause: deployment cube validation checked that referenced metric nodes and dimension attributes exist, but per-cube validation did not fail when a declared dimension was absent from the dimension-link graph of a metric's ultimate non-metric parent. That allowed dj push to create or update a syntactically valid cube whose metric parent transforms could not join to every declared dimension, with the failure surfacing later during SQL generation.

Approach:

• Resolves each cube metric to its unique ultimate non-metric parent revisions during bulk cube validation.
• Builds one batched dimension reachability map for all cube parent revisions and declared cube dimension node names.
• Checks each declared dimension attribute, including role-qualified references, against every parent revision used by the cube metrics during per-cube validation.
• Appends INVALID_DIMENSION errors for missing paths before creating the cube revision.
• Keeps existing existence/status validation and cube metadata construction unchanged.

Files modified:

• datajunction-server/datajunction_server/internal/deployment/orchestrator.py
• datajunction-server/tests/internal/deployment/orchestration_test.py
• fix_plan.json

LOC: +82 / -30

ruff check datajunction-server/datajunction_server/internal/deployment/orchestrator.py datajunction-server/tests/internal/deployment/orchestration_test.py reports no new findings on the changed files.
Ran pytest -x locally with no new failures.

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