Copy request as cURL to clipboard from the context menu

[giemic8]

Is your feature request related to a problem? Please describe.

There is no quick way to hand a request from Trufos to the terminal or a colleague. The full code generator (#775) covers this eventually, but a lightweight "copy as cURL" needs no modal, no language selector and no new UI surface — it fits into the existing request context menu (Rename / Copy / Delete Request).

Describe the solution you'd like

Add a "Copy as cURL" entry to the request context menu in the sidebar (RequestDropdown), between "Copy Request" and "Delete Request". Clicking it builds a cURL command from the request and writes it to the clipboard, with a success toast.

Generated command:

• curl -X <METHOD> '<url>' with the URL built from base + query params.
• One -H 'Key: value' per active header.
• Body:
  • Text body: --data-raw '<content>' (content read from the request body file via the existing IPC stream; missing/empty body file → no data flag). Adds -H 'Content-Type: <mimeType>' when no active Content-Type header is set.
  • File body: --data-binary @'<path>' when a file path is set.
  • Form-data: -F 'key=value' / -F 'key=@path' per active field.
• Values are single-quote shell-escaped (' → '\''), multi-part commands are joined with \ line continuations for readability.
• Template variables ({{...}}) are copied unresolved — the command is meant to be portable and must not leak resolved secrets.

Describe alternatives you've considered

• Waiting for the full code generator (Code Generator – Export Requests as Code Snippets #775) — bigger scope (modal, multiple languages, resolved variables); this ticket is the minimal context-menu shortcut and can later delegate to the generator's curl target.

Acceptance criteria

• "Copy as cURL" appears in the request context menu and writes the command to the clipboard.
• Active-only headers, correct shell escaping, all three body types handled.
• Works for requests whose body file does not exist yet (never opened).
• Success feedback via toast; failures surface via the existing error handler.
• Unit tests for the command builder and the menu action.