* types: add optional context parameter to generatePullRequestDescription signature
* api: update gitApi to pass optional context to PR description generation
* http: include trimmed context in PR description API request body
* ui: add additional context input for PR generation with desktop disclosure and mobile sheet
* desktop: pass optional context to Tauri generate_pr_description command
* tauri: add optional context parameter and inject into PR description prompt
* server: read optional context from request and inject into PR description prompt
* vscode: update type signature for context parameter (compatibility only)
* fix(vscode): drop context from pr-description payload
Remove context field from PR description payload
Send only base and head to the bridge API for PR descriptions
Clarify payload compatibility across web/desktop environments