feat: add opt-in resumable SQLite RBU support

[aballiet]

Summary

• add opt-in rbu: true build configuration for Android CMake, CocoaPods, and SwiftPM
• expose top-level isRBUEnabled() and asynchronous applyRBU() APIs
• support bounded stepping, persistent state files, pause/resume, progress/state reporting, and structured SQLite error codes
• document artifact ownership, recovery behavior, exact-base requirements, and SQLite RBU limitations
• add synthetic end-to-end and validation/error coverage

RBU remains disabled by default and supports OP-SQLite's bundled vanilla SQLite backend. Configuring the dedicated toggle with SQLCipher, libSQL, Turso, or Apple's embedded SQLite fails at build time. Web and the Node test facade expose capability detection and a clear unsupported error.

sqliteFlags: "-DSQLITE_ENABLE_RBU=1" remains available for low-level configuration. The dedicated toggle is preferred because it validates backend compatibility.

API

const result = await applyRBU({
  targetPath: "/absolute/path/target.sqlite",
  updatePath: "/absolute/path/update.sqlite",
  statePath: "/absolute/path/update-state.sqlite",
  maxSteps: 100,
});

The native worker performs at most 1000 steps by default and always closes the RBU handle, including error paths. A paused close persists SQLite's resume state; a completed update returns status: "complete" and state: "done".

Verification

• Android release build for all configured ABIs
• Android runtime suite with RBU enabled, including bounded pause, separate state creation, resume, atomic target visibility, already-complete behavior, missing artifacts, and malformed artifacts
• Android runtime suite with RBU disabled
• TypeScript typecheck, package build, Node tests, web production build, and Docusaurus production build
• CocoaPods Ruby syntax validation and SwiftPM manifest parsing

Local Apple compilation/runtime testing was unavailable in this environment; CI should exercise the CocoaPods and SwiftPM paths.

Build impact

Disabled builds do not compile the RBU extension. Enabled builds add SQLite's bundled RBU implementation and a small JSI adapter; no additional native dependency or SQLite library is linked.

Closes #452

[ospfranco]

I will merge this if there is more support or sponsorship, otherwise I'm stuck supporting this for years.

[aballiet]

I will merge this if there is more support or sponsorship, otherwise I'm stuck supporting this for years.

OK got it! 😊