Land T1.33: part 1, real-dataset diversity (T1.32f folded in)

Part 1 of T1.33 (the owner folded T1.32f into T1.33): the AdventureWorks
churn (binary) and products.Color (multiclass) questions admitted as
acceptance cases with base.adventureworks's routes (churn's query
normalized, held to the notebook's parsed question); the RelBench recipe
(relbench.py) refusing any path inside any git work tree by file
identity, every concrete path preflighted and re-guarded, DuckDB's spill
under the cache, no data committed; differential.py's classifier
tightened (only text_time an allowed core refusal; a rejected entry
classifies nothing; the corrected-reference path refuses malformed
records and crashes). The RelBench differential over rel-hm, rel-stack,
rel-avito and rel-trial (22 sources): no crash, no INTERNAL_ERROR,
nothing unclassified (14 agree, 2 P1B-13, 3 P1B-3, 3 P1B-2; text_time
P1B-2 vs DT-17 is an open owner item). E87. Tests by a separate test
author. 2 review rounds. Rebased onto f5826d8 by hand (tracker
conflict), confirmed by both reviewers.

Candidate run 38565674956 green at
206e44c; this commit changes no file,
so the phase branch moves at once and its own runs are recorded
afterwards (E43 (b)).

Reviewed-by: independent reviewer (fresh agent) and Codex, T1.33
Protected-paths: contract/baselines/ref-pandas3/python-core.jsonl; contract/baselines/ref-pandas3/python-old.jsonl; contract/baselines/ref-pandas3/rust-host.jsonl; contract/cases/s1/base.adventureworks.churn.json; contract/cases/s1/base.adventureworks.color.json; contract/reference/b413e9ad6c613e82e5f1fc2ad0bc152870f59e74.jsonl; contract/tests/t133-pending.json; contract/tests/t133_gate.py; contract/tests/test_t133_adventureworks_cases.py; contract/tests/test_t133_corrected_controls.py; contract/tests/test_t133_differential_classes.py; contract/tests/test_t133_relbench_recipe.py; tests/test_contract_cases.py
Base-SHA: 9e0282a
Checkpoint-SHA: 9e0282a
Signed-off-by: Adi Wadaskar <awadaskar@nvidia.com>

Author: adi-kumo