refactor(tui): theme switching & loading reactivity

[nihil2501]

Issues

• Prepares for[FEATURE]: Custom themes can use calculated system colors #6322
  • Shown in GIF below

Refactor

Remodels theme resolution reactivity with respect to this tuple:

• The user's requested theme
• The loading status of relevant async resources

This change also prepares for a feature, system-like custom themes, shown in this video:

Fixes

• Theme picker list now updates on reload
• Warning toasts on errored
  • These toasts could easily be removed

Performance

The theme context now readies 10x faster (30ms → 3ms) in by-far the most common case: using one of the default themes. The speedup is achieved by not waiting on resources irrelevant to the requested theme before marking it as ready.
Timed using this patch that calls console.time inside createSimpleContext.

After = 3.558ms

...
[17:05:25] [LOG] '%s: %s' 'context:Theme' '3.558ms'
...

Before = 31.264ms

...
[17:04:19] [LOG] '%s: %s' 'context:Theme' '31.264ms'
...

Implementation

• 2x createResources
  • Custom theme loading
  • System palette detection
• These in turn are accessed in a createMemo returning this tuple:
  • The user's requested theme
  • The loading status of relevant async resources
• 2x createEffects
  • One to update the requested theme when the config generation increments
  • Another to promote and re-resolve the theme when our memoized tuple changes

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

[nihil2501]

Closed #9184 in favor of this in order to incrementally introduce an atomic foundational change before considering adding a feature on top of it.

[nihil2501]

cc @thdxr@rekram1-node this TUI theme reactivity remodel was developed while some of the Omarchy theme changes were being added, so this may be of interest / fresh in your minds.

The short Fixes and Performance sections in the PR description discuss the concrete improvements.

[github-actions]

Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.