chore(a11y): add lint rule flagging icon-only buttons without accessible name

BaseButton renders a bare button and does not enforce a name, so icon-only
usages without aria-label are announced as just "button" — the a11y audit
found this pattern regenerating across the codebase (42 current instances,
including the TipTap bubble menu where v-tooltip provides no accessible
name). The new vikunja/icon-button-accessible-name rule flags icon-only
BaseButton/XButton usages that have no aria-label, aria-labelledby, title,
visible text, or sr-only text; unknown child components are assumed to
render text to avoid false positives.

Set to 'warn' until the existing instances get aria-labels, then raise to
'error'.

Claude-Session: https://claude.ai/code/session_018prq5WqRL38EGhPNQKqZUP

frontend/eslint-rules/icon-button-accessible-name.js

@@ -0,0 +1,118 @@
+/**
+ * Flags icon-only buttons without an accessible name.
+ *
+ * BaseButton renders a bare <button>/<a> and does not enforce a name, so an
+ * icon-only usage without aria-label is announced as just "button" (WCAG 1.1.1
+ * / 4.1.2). Same for XButton's icon-only mode. Visible text, {{ }} content,
+ * sr-only spans, aria-label(ledby) or title all count as a name; unknown child
+ * components are assumed to render text so the rule only fires on clearly
+ * icon-only content.
+ */
+
+const NAME_ATTRS = new Set(['aria-label', 'aria-labelledby', 'title'])
+const ICON_ELEMENTS = new Set(['Icon', 'icon', 'svg', 'i'])
+// Plain containers we can safely look through for text
+const TRANSPARENT_ELEMENTS = new Set(['span', 'div', 'template'])
+
+function attrName(attr) {
+	if (!attr.directive) {
+		return attr.key.rawName ?? attr.key.name
+	}
+	if (attr.key.name.name === 'bind' && attr.key.argument?.type === 'VIdentifier') {
+		return attr.key.argument.rawName ?? attr.key.argument.name
+	}
+	return null
+}
+
+function hasNameAttr(element, extra = []) {
+	return element.startTag.attributes.some(attr => {
+		if (attr.directive && ['text', 'html'].includes(attr.key.name?.name)) {
+			return true
+		}
+		const name = attrName(attr)
+		if (name === null || !(NAME_ATTRS.has(name) || extra.includes(name))) {
+			return false
+		}
+		// static attr must be non-empty; bound attrs are trusted
+		return attr.directive || (attr.value != null && attr.value.value.trim() !== '')
+	})
+}
+
+function getAttr(element, name) {
+	return element.startTag.attributes.find(attr => attrName(attr) === name)
+}
+
+function contentProvidesName(element) {
+	for (const child of element.children) {
+		if (child.type === 'VText' && child.value.trim() !== '') {
+			return true
+		}
+		if (child.type === 'VExpressionContainer') {
+			return true
+		}
+		if (child.type === 'VElement') {
+			if (child.rawName === 'slot' || child.rawName === 'component') {
+				return true
+			}
+			if (hasNameAttr(child, ['alt'])) {
+				return true
+			}
+			if (ICON_ELEMENTS.has(child.rawName)) {
+				continue
+			}
+			if (TRANSPARENT_ELEMENTS.has(child.rawName)) {
+				if (contentProvidesName(child)) {
+					return true
+				}
+				continue
+			}
+			// Unknown component — assume it renders text
+			return true
+		}
+	}
+	return false
+}
+
+export default {
+	meta: {
+		type: 'problem',
+		docs: {
+			description: 'require an accessible name on icon-only BaseButton/XButton usages',
+		},
+		messages: {
+			missingName: 'Icon-only <{{component}}> has no accessible name — screen readers announce it as just "button". Add aria-label (translated via $t) or visible/sr-only text.',
+		},
+		schema: [],
+	},
+	create(context) {
+		const sourceCode = context.sourceCode ?? context.getSourceCode()
+		const services = sourceCode.parserServices
+		if (!services?.defineTemplateBodyVisitor) {
+			return {}
+		}
+
+		function check(node, component) {
+			if (hasNameAttr(node) || contentProvidesName(node)) {
+				return
+			}
+			context.report({
+				node: node.startTag,
+				messageId: 'missingName',
+				data: {component},
+			})
+		}
+
+		return services.defineTemplateBodyVisitor({
+			'VElement[rawName="BaseButton"]'(node) {
+				check(node, 'BaseButton')
+			},
+			'VElement[rawName="XButton"]'(node) {
+				// XButton is only icon-only when it has an icon prop and no slot content
+				if (getAttr(node, 'icon') === undefined) {
+					return
+				}
+				check(node, 'XButton')
+			},
+		})
+	},
+}

frontend/eslint.config.js

@@ -4,6 +4,7 @@ import vueTsEslintConfig from '@vue/eslint-config-typescript'
 import pluginDepend from 'eslint-plugin-depend'
 import { fileURLToPath } from 'node:url'
 import { dirname } from 'node:path'
+import iconButtonAccessibleName from './eslint-rules/icon-button-accessible-name.js'
 
 const __dirname = dirname(fileURLToPath(import.meta.url))
 
@@ -18,7 +19,17 @@ export default [
 		],
 	},
 	{
+		plugins: {
+			vikunja: {
+				rules: {
+					'icon-button-accessible-name': iconButtonAccessibleName,
+				},
+			},
+		},
 		rules: {
+			// TODO(a11y): raise to 'error' once the 42 existing unnamed icon buttons have aria-labels (ACR follow-up)
+			'vikunja/icon-button-accessible-name': 'warn',
+
 			'quotes': ['error', 'single'],
 			'comma-dangle': ['error', 'always-multiline'],
 			'semi': ['error', 'never'],