epic: SQE catalog — replace sqlx-sqlite with sqlite-rs for internal metadata

[iheitlager]

Use Case

sqlite-rs as SQE's internal catalog storage — metadata for tables/indexes when no remote catalog is configured.

Context

SQE uses SQLite via sqlx-sqlite for the Iceberg SQL catalog. Currently depends on the C amalgamation via libsqlite3-sys. sqlite-rs could eliminate:

• C toolchain requirement for cargo install sqe-cli
• links = "sqlite3" collision (concurrency: multi-reader single-writer #389)
• C CVE surface in the catalog path

Current State

SQE's SQLite usage:

• All access via sqlx, inside vendored Iceberg catalog
• Four consumers: sql-sqlite catalog backend, embedded warehouse, ATTACH ... TYPE sqlite, test-sqlite coordinator
• Low QPS (metadata path) — correctness critical, not perf critical

Gaps

1. No consumable API — Need Connection/Statement facade
2. Bound parameters — sqlx uses query(...).bind(...) throughout
3. Send pager — Pager is Rc/RefCell, blocks tokio pool

Path

1. Probe: sqlite-rs query/dump on SQE warehouse, diff against sqlite3
2. Corpus: Add SQE catalog statements to oracle suite
3. API facade: Connection/Statement with prepare(), bind()
4. Bounded integration: embedded warehouse only (single-process)
5. Send pager: thread-safe for sqlx pool
6. sqlx driver: full swap

Success

• Reads/writes SQE warehouses identically to sqlite3
• Public API with bind support
• Send + Sync pager
• sqlx-sqlite-rs driver passes catalog tests