[MC-464-A] Consolidate export canonical lexeme selection

[TarahAssistant]

MC Task: MC-464 — Consolidate survey-overlapping concepts on export / Lane MC-464-A

Fixes #654.

Current consolidate:true findings

• export_complete_lingpy_dataset already accepts consolidate and forwards it to both export_lingpy_tsv and export_nexus; conceptTag also implies consolidation.
• The low-level consolidated path groups duplicate survey concept IDs through compare.consolidated_matrix, collapses only byte-identical committed cognate partitions, and keeps differing partitions as suffixed gloss#id characters with warnings.
• Before this PR, the consolidated LingPy TSV de-duplicated one form per (meaning, doculect) by earliest timestamp only; it did not honor manual_overrides.canonical_lexemes when both survey forms existed for the same speaker.

Change

• Thread manual_overrides.canonical_lexemes into consolidated LingPy wordlist generation.
• When multiple survey forms collapse onto one (meaning, doculect), prefer the explicitly selected canonical CSV row; fall back to the existing earliest-start behavior when no selection exists.
• Add a fixture-only round-trip test for complete export: two safe overlapping meanings collapse to N concept blocks instead of 2N duplicate gloss#id blocks, a disagreeing meaning stays split with warnings, and the canonical lexeme selection chooses the selected form.

Validation

• PYTHONPATH=python python3 -m pytest python/ai/tools/test_consolidated_export_wiring.py::test_complete_export_consolidate_roundtrip_collapses_n_not_2n -q → 1 passed in 0.05s
• PYTHONPATH=python python3 -m pytest python/ai/tools/test_consolidated_export_wiring.py python/ai/test_workflow_tools.py -q → 18 passed in 0.08s
• PYTHONPATH=python python3 -m pytest python/ -q → 1926 passed, 6 skipped, 1 warning, 3 subtests passed in 34.45s
• uvx ruff check python/ --select E9,F63,F7,F82 → All checks passed!
• git diff --check → clean

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