switch to browser base64 methods

[BwayCer]

Use native browser APIs to solve this issue.

[zero-gear]

The issue described in #8 was reproducible on my iPhone 12 Pro (no diagrams were rendered).

After applying this patch, all diagrams from kroki-test.md render correctly, except that the Diagrams.net type is still not rendered.

Thank you, @BwayCer — your changeset is both essential and very helpful for me.

[gregzuro]

Thanks @BwayCer — taken in 1.3.0 (#29, https://github.com/gregzuro/obsidian-kroki/releases/tag/1.3.0).

The implementation is slightly hardened from this PR: btoa(String.fromCharCode(...compressed)) can blow the call stack for large diagrams (the spread blows past the engine's argument limit), so the new code builds the binary string in 0x8000-byte chunks and then btoas once:

let binary = "";
const chunkSize = 0x8000;
for (let i = 0; i < compressed.length; i += chunkSize) {
    binary += String.fromCharCode(...Array.from(compressed.subarray(i, i + chunkSize)));
}
return btoa(binary).replace(/\+/g, "-").replace(/\//g, "_");

Same effect, won't choke on big diagrams. Closing — your fix is in the release.