build(lint): upgrade vue ruleset to ‘recommended’

[pataar]

This expands the ruleset currently used for Vue. These fixes have been applied automatically.

I mainly made changes to .eslintrc.json. Had to fix one rule manually in SystemPanel.vue. As key and index were used twice, which might be confusing.

Also some rules have been disabled, as they're hard to fix right now and are not that important.

[github-actions]

Size Change: -39 B (0%)

Total Size: 1.78 MB

Filename	Size	Change
./dist/assets/Codemirror.js	113 kB	-2 B (0%)
./dist/assets/Heightmap.js	120 kB	-2 B (0%)
./dist/assets/index.js	247 kB	-33 B (0%)
./dist/assets/Viewer.js	282 kB	-3 B (0%)
./dist/sw.js	6.26 kB	+1 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/assets/Codemirror.css	20 B
./dist/assets/Heightmap.css	74 B
./dist/assets/index.css	56.4 kB
./dist/assets/materialdesignicons-webfont.woff2	354 kB
./dist/assets/vendor.js	440 kB
./dist/assets/vendor.css	64.5 kB
./dist/assets/Viewer.css	318 B
./dist/config.json	25 B
./dist/fonts/roboto-black.woff2	11 kB
./dist/fonts/roboto-bold.woff2	11 kB
./dist/fonts/roboto-light.woff2	11.2 kB
./dist/fonts/roboto-medium.woff2	11.1 kB
./dist/fonts/roboto-regular.woff2	11 kB
./dist/fonts/roboto-thin.woff2	11 kB
./dist/img/icons/apple-touch-icon-152x152.png	4.38 kB
./dist/img/icons/favicon-16x16.png	569 B
./dist/img/icons/favicon-32x32.png	1.05 kB
./dist/img/icons/icon-196-png	3.97 kB
./dist/img/icons/icon-512-png	11.1 kB
./dist/img/icons/mstile-150x150.png	4.26 kB
./dist/img/klipper.svg	3.4 kB
./dist/img/logo.svg	4.08 kB
./dist/img/sidebar-background.svg	1.33 kB
./dist/index.html	692 B

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