Chore: fix sonar warnings

[waffles-dev]

Fix most warnings in sonarqube, disabled following rules:

    "sonarlint.rules": {
        "typescript:S6353": {
            "level": "off"
        },
        "typescript:S7728": {
            "level": "off"
        },
        "css:S4667": {
            "level": "off"
        },
        "Web:S6851": {
            "level": "off"
        },
        "typescript:S7764": {
            "level": "off"
        }
    },

some rules had to be ignored as they cause errors. no huge changes, biggest change in Apps.vue where custom app icon is loaded, but all logic/flow should be equivalent