Evaluate extracting inline dashboard JavaScript into static assets

[raychrisgdp]

Goal

Evaluate and, if useful, extract large inline dashboard JavaScript from templates/index.html into static assets after backend route cleanup is underway.

Candidate Scope

• Move reusable dashboard behavior into static/ modules or scripts.
• Keep template-rendered HTML readable and compact.
• Preserve source-provenance UI, keyboard/tap affordances, and simulated mode.

Constraints

• This should happen after or alongside route cleanup only if it stays small.
• Avoid visual redesign in the same PR.
• Keep accessibility behavior intact.

Verification

• Existing template tests pass or are updated for the new static asset contract.
• Simulated dashboard smoke check still works.