replace btoa with UTF-8 Base64 to resolve i18n error dialog crashes

[SharpIceX]

fix:

Uncaught (in promise) InvalidCharacterError: Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.
    at Fac ((Plugin):cpm_plugin.js:2260:536)
    at d.Y3b ((Plugin):cpm_plugin.js:2015:60)
    at d ((Plugin):cpm_plugin.js:18:47)
Fac	@	(Plugin):cpm_plugin.js:2260
Y3b	@	(Plugin):cpm_plugin.js:2015
d	@	(Plugin):cpm_plugin.js:18
Promise.catch		
U3b	@	(Plugin):cpm_plugin.js:2013
d	@	(Plugin):cpm_plugin.js:18
（匿名）	@	file_system.ts:224
e	@	file_system.ts:166
i	@	file_system.ts:109
v3b	@	(Plugin):cpm_plugin.js:1998
F6b	@	(Plugin):cpm_plugin.js:2109
bac	@	(Plugin):cpm_plugin.js:2239
d	@	(Plugin):cpm_plugin.js:18
Ze	@	vue.min.js:11
B	@	vue.min.js:11
K6.G._wrapper	@	vue.min.js:11

As noted in the MDN Window.btoa() documentation, btoa() only supports ASCII and lacks built-in Unicode support. This causes errors when processing non-ASCII characters, including internationalized (i18n) text.

Before fix:

default.mp4

After fix:

default.mp4