fix: differentiate cache label from cache size label in TaskHeader

[roomote]

This PR fixes a UI issue where two different elements in the TaskHeader component both displayed "Cache" as their label, causing confusion.

Problem

• Two rows in TaskHeader both showed "Cache" as the label
• First row (line 241): displays cache token metrics (writes/reads)
• Second row (line 272): displays cache size in bytes
• This duplication was confusing for users

Solution

• Added a new translation key cacheSize to differentiate the cache size display from the cache token metrics
• Updated TaskHeader.tsx to use t("chat:task.cacheSize") for the byte size display
• Kept the original t("chat:task.cache") for the token metrics display
• Updated all 18 language translation files with appropriate translations

Changes

• Modified webview-ui/src/components/chat/TaskHeader.tsx to use the new translation key
• Added cacheSize translation to all language files in webview-ui/src/i18n/locales/*/chat.json

Testing

• ✅ All tests pass (968 passed, 1 skipped)
• ✅ TypeScript compilation successful
• ✅ ESLint checks pass

This minimal change preserves existing functionality while improving clarity in the UI.

---

Important

This PR differentiates cache token metrics and cache size labels in TaskHeader.tsx by introducing a new translation key cacheSize and updating all language files.

• Behavior:
  • Differentiates cache token metrics and cache size labels in TaskHeader.tsx by using t("chat:task.cacheSize") for cache size.
  • Retains t("chat:task.cache") for cache token metrics.
• Translations:
  • Adds cacheSize translation key to all language files in webview-ui/src/i18n/locales/*/chat.json.
• Testing:
  • All tests pass (968 passed, 1 skipped).
  • TypeScript compilation successful.
  • ESLint checks pass.

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[roomote]

Reviewing my own code is like debugging in a mirror—everything looks backward but somehow makes sense.

[roomote]

Good fix! This correctly differentiates the cache size display from the cache token metrics above.

Minor suggestion: Could we add a brief comment here explaining the multiplication by 4? Something like:

Suggested change

	{prettyBytes(((cacheReads || 0) + (cacheWrites || 0)) * 4)}
	{t("chat:task.cacheSize")}
	</th>
	<td className="align-top">
	{/* Each token is approximately 4 bytes */}
	{prettyBytes(((cacheReads || 0) + (cacheWrites || 0)) * 4)}

This would help future developers understand the calculation.

[roomote]

Is the title case "Cache Size" intentional here? I noticed some other languages use sentence case (e.g., Spanish: "Tamaño de caché"). Not a blocker, just curious about the consistency across translations.