feat: add InvalidatePricingCache function and call it in updateOption

[0-don]

When updating model ratios or prices via the /api/option/ endpoint, the /api/pricing endpoint continues returning stale cached data for up to 1 minute.

This PR adds cache invalidation when ratio-related options are updated, ensuring the pricing endpoint immediately reflects the new values.

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Pricing information now automatically refreshes when pricing or ratio options are updated, ensuring accurate and current pricing data is always displayed.

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[coderabbitai]

Walkthrough

A new public function InvalidatePricingCache() is introduced to force pricing cache refresh. Calls to this function are added after updates to pricing-related options (ModelRatio, GroupRatio, CompletionRatio, ModelPrice) to ensure the cache reflects the latest configuration values.

Changes

Cohort / File(s)	Summary
Pricing cache invalidation mechanism model/pricing.go	Added InvalidatePricingCache() public function that acquires lock and resets lastGetPricingTime to zero, forcing cache refresh on next access
Option updates with cache invalidation model/option.go	Integrated calls to InvalidatePricingCache() after ModelRatio, GroupRatio, CompletionRatio, and ModelPrice option updates to invalidate stale pricing data

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A cache grows stale, but fear not dear friend,
When prices update, we now make amend!
Invalidate, refresh, let the fresh data flow,
No more serving yesterday's pricing show! 💰

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding InvalidatePricingCache function and calling it in updateOption.

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✨ Finishing touches

• 📝 Generate docstrings

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[0-don]

Closing — the InvalidatePricingCache change was already merged, and the remaining i18n commit is covered by #2958.