feat: Star on github popup in Rill developer

[k-anshul]

• Nudges a user to star Rill's repo on dashboard load once every 24 hours.
• If user clicks on star/don't show this again then nudge is never shown (unless user clears local memory).

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!

[AdityaHegde]

Approving with a couple of nits

[AdityaHegde]

nit: do we need a getter here? Cant we just use this.store.value directly?

[k-anshul]

store is private so can't be used in tests directly.

[AdityaHegde]

nit: same here, we just add isVisible on this class that checks this.store.value

Or if we want reactivity on visible this might be better,

this.visible = $derived.by(() => {
  const now = ...
  if (this.store.value.status !== "armed") return false;
  return !this.store.value.mutedUntil || this.store.value.mutedUntil <= now;
})

[k-anshul]

Inlined it into the getter and dropped the standalone helper. Kept it as a getter rather than $derived: store.value is $state, so the getter already re-renders consumers on state changes, and $derived would cache the Date.now() comparison, so the one-day mute wouldn't expire until some unrelated state change invalidated it.