feat: Add WebAssembly (WASM) compiler target and browser CDN support

[devgabrielmarcondes]

This PR introduces the foundation for adapting pdf-inspector to run fully client-side on browsers via WebAssembly (WASM).

Changes:

• Conditionally disabled the rayon threading dependency strictly for wasm32 environments (as WebAssembly forbids multi-threading/OS threads by default).
• Implemented a mocked CompatInstant fallback using js_sys::Date::now() to resolve the RuntimeError: unreachable fatal error occurring during WASM compilation from std::time::Instant::now().
• Explicitly enabled the wasm_js feature for the getrandom crate exclusively for cfg(target_arch = "wasm32").
• Exported the core process_pdf_mem logic through the wasm-bindgen API in a new src/wasm.rs module.
• Added a full demo client wasm-demo/index.html showcasing the direct conversion happening purely client-side without OCR delays.

Demo (WASM running pure client-side processing)

[abimaelmartell]

Hi, this is very impressive, thanks for the contribution!

I can't review your code because your first commit changed every file here. I suspect your code editor might have modified line endings or something else. Can you clean it up so i can review it?

Thanks,

Best,
Abimael Martell

[devgabrielmarcondes]

Hi Abimael,

Sorry about that! My Windows Git automatically checked out CRLF line endings across the whole repo on my initial clone without me noticing.

I just force-pushed a clean version with only the 4 intended file modifications (with correct LF endings) and a single clean commit. It should be perfect for review now!

Please let me know if everything looks good. Thanks!

[abimaelmartell]

Thanks for putting this together, the WASM direction is definitely useful.

One blocker: the WASM lopdf dependency still enables its default features, and cargo tree --target wasm32-unknown-unknown -e features shows that lopdf/default still pulls in lopdf/rayon and rayon. So this doesn’t fully disable threading for WASM yet.

Could you change the wasm target dependency to use default-features = false and then explicitly re-enable any non-threading features we still need? Also please run cargo fmt, since src/wasm.rs currently fails cargo fmt --check.

Thanks!

[devgabrielmarcondes]

Thanks for the review!

I've just pushed an update addressing your feedback:

• Explicitly set default-features = false for the wasm32 lopdf dependency to remove rayon.
• Re-enabled the non-threading default features (chrono, jiff, and time).
• Ran cargo fmt across the project to ensure everything follows the formatting standards.

Let me know if there's anything else needed!