Fix WAL-mode Cursor state.vscdb auth (unable to open database file)

[CodyKoInABox]

Problem

0.3.1 switched from sql.js (load file into memory) to node-sqlite3-wasm (open on disk) so state.vscdb files over 2 GiB still authenticate.

Cursor keeps state.vscdb in WAL mode. That WASM build cannot open WAL databases at all. Querying it throws:

Could not read Cursor session from local DB: unable to open database file

That hits every install, not just huge DBs. Confirmed locally: native sqlite3 WAL file, header bytes 18/19 = 2, in-place open fails; copy + strip WAL flag on the copy succeeds.

Fix (0.3.2)

• If the SQLite header says WAL (or in-place open fails with CANTOPEN/BUSY), copy to a temp file (COPYFILE_FICLONE when the FS supports it), set format-version bytes to rollback on the copy only, then query.
• Never writes Cursor’s live database.
• Non-WAL files still open in place (no multi-GiB copy).
• Decode ItemTable BLOBs as UTF-8. VS Code stores those values as blobs; treating them as strings only would fail after the WAL open started working.

Tests

• Existing ItemTable + >2 GiB sparse-file tests
• WAL header stamp: raw WASM open throws unable to open database file; readAuthFromStateDb still returns the token and does not mutate the source file
• BLOB UTF-8 decode
• Native sqlite3 WAL fixture with sidecars (skipped if sqlite3 is missing)

npx tsc --noEmit, npx vitest run (28 tests), npm run compile, vsce package all green locally.

Release

Version bumped to 0.3.2. After merge, tag v0.3.2 so release.yml publishes to Open VSX and creates the GitHub release.