fix: back-port KEY as a bare identifier (PRIMARY/FOREIGN KEY via expect_bareword_ci) from t-rust-db/db-core — partial #696

[iheitlager]

Description

Partial fix for #696 that t-rust-db/db-core already carries (t-rust-db/db-core parser::row, found by diffing against this crate for t-rust-db/db-core#84): KEY is removed from the reserved keyword table and PRIMARY KEY / FOREIGN KEY match it as a case-insensitive bare word instead (Parser::expect_bareword_ci). Result: SELECT key FROM regions and … ON orders.region_key = regions.key parse — the exact case #696 names as blocking SQE's key column.

Tests in db-core: primary_key_matches_case_insensitively, key_is_usable_as_a_column_name.

Back-port here first (Lab271 is leading; the port must converge, see t-rust-db/db-core#84), then #696 can continue with the remaining 88 %fallback keywords using the same expect_bareword_ci mechanism.

Complexity

Estimate: trivial — one keyword-table entry, one helper, two call sites, two tests.

Acceptance Criteria

• KEY gone from tokenizer.rs's keyword table; expect_bareword_ci in grammar.rs
• Both db-core tests pass here; existing ddl_parser tests unchanged
• bug: 89 keywords are reserved that SQLite treats as identifiers (parse.y's %fallback) — blocks SQE's 'key' column #696 updated to note KEY is done and the mechanism to reuse

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🤖 Analysis by Claude