feat(i18n): translate all Hebrew (he) locale files from English to Hebrew

Translates all 17 Hebrew locale files (7 backend + 10 webview-ui)
from English template strings to proper Hebrew translations.

Backend files:
- src/i18n/locales/he/common.json
- src/i18n/locales/he/embeddings.json
- src/i18n/locales/he/marketplace.json
- src/i18n/locales/he/mcp.json
- src/i18n/locales/he/skills.json
- src/i18n/locales/he/tools.json
- src/i18n/locales/he/worktrees.json

WebView UI files:
- webview-ui/src/i18n/locales/he/chat.json
- webview-ui/src/i18n/locales/he/cloud.json
- webview-ui/src/i18n/locales/he/common.json
- webview-ui/src/i18n/locales/he/history.json
- webview-ui/src/i18n/locales/he/marketplace.json
- webview-ui/src/i18n/locales/he/mcp.json
- webview-ui/src/i18n/locales/he/prompts.json
- webview-ui/src/i18n/locales/he/settings.json
- webview-ui/src/i18n/locales/he/welcome.json
- webview-ui/src/i18n/locales/he/worktrees.json

All placeholders ({{variable}}) preserved exactly as in English source.
Technical terms and brand names kept in English where appropriate.
Validation script confirms no missing translations.

Author: roomote