docs(hhtl): PR-X14′ pre-sprint prompt — lance-graph-contract::column + bridge

Companion to the GridLake prompt (ade8edb). Names the four current
duplicate column-access patterns (BindSpace Box<[u64]>, lance-graph query
HashMap<String, RecordBatch>, planner Morsel placeholder enum,
lance::Dataset.scan rolled per feature) and the contract crate already
exists (lance-graph-contract, 10+ consumers) but lacks a column module.

PR-X14′ adds a column/ module set to the existing lance-graph-contract
crate (preserving its zero-dep invariant — adds ndarray path dep only;
no arrow/lance/datafusion in the contract crate) and a new sibling
lance-graph-contract-bridge crate that bridges Lance + Arrow into
MultiLaneColumn. SQL path + lance-graph's datafusion deps stay
untouched per the 2026-05-19 deferred-SQL decision.

Q-NEW-2 marker: plan-review savant picks path α (concurrent with
GridLake at W2.5, 10 workers) vs path β (sequential at W3, 4 workers +
0.5 week schedule extension).

File evidence cited verbatim from current tree:
- lance-graph-contract/src/lib.rs:1-12 (zero-dep claim)
- cognitive-shader-driver/src/bindspace.rs:36-44 (Pattern 1)
- lance-graph/src/query.rs:243 + sql_query.rs:69 (Pattern 2)
- lance-graph-planner/src/physical/mod.rs:37-58 (Pattern 3 placeholder)
- holograph + lance-graph-ontology optional lance deps (Pattern 4)

Author: claude