Tidy Vue templates and linting config

[BeardedBear]

Add eslint-plugin-vue; wrap console.error calls with DEV checks. Fix template formatting and attribute ordering (v-if/v-for/key placement, self-closing tags), and adjust some prop/type defaults to satisfy lint rules and prevent runtime issues.

[claude]

Code review

Commit Message Format Issue

The first commit in this PR does not follow the Conventional Commits specification required by AGENTS.md.

Current commit message:

Tidy Vue templates and linting config

Issue: Missing type prefix and not using standard imperative verb.

Should be something like:

refactor(lint): tidy Vue templates and linting config

or

style(vue): tidy templates and linting config

The other commits in this PR correctly follow the format:

• ✅ docs: Remove CLAUDE and copilot instructions
• ✅ docs(agents): Rename and expand agent guidance

Consider amending the first commit message to follow the Conventional Commits format before merging.

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Other findings:

• ✅ No bugs detected
• ✅ Code changes follow project conventions
• ✅ Security improvement: DOMPurify sanitization added in ArtistInfo.vue