frontend: add Codecov Bundle Analysis when a production bundle pipeline exists

[oaslananka]

Context

Codecov Bundle Analysis can report asset/module size changes for Rollup, Vite, Webpack, or a file-tree bundle analyzer. The current desktop frontend and dashboard are inline/static HTML and do not have a production JavaScript module bundle. Introducing a bundler solely to produce telemetry would add dependencies without a meaningful module graph.

Scope

• Trigger this work when the shipped frontend adopts a real production bundle pipeline or multiple generated assets.
• Integrate the appropriate Codecov bundler plugin or bundle-analyzer CLI into the canonical production build.
• Use GitHub OIDC or public-repository tokenless authentication; do not add a new long-lived upload secret.
• Disable plugin telemetry.
• Start with an informational bundle-size status and a documented warning threshold.
• Cover the Tauri frontend and any extracted dashboard assets that are actually shipped.

Acceptance criteria

• The report is generated from the same production build output that is shipped.
• PRs show total, gzip, and module/asset size deltas.
• The integration is pinned and covered by dependency/workflow policy checks.
• Telemetry is explicitly disabled.
• The initial status is informational and has a documented threshold and rollback path.
• No bundler is introduced only for reporting.

Evidence required

Successful CI upload, Codecov bundle view/PR status, production artifact mapping, and before/after size report.

Non-goals

Treating the current single inline HTML files as a JavaScript module graph or making bundle size blocking before a stable baseline exists.