Pasting with the terminal's own paste goes in as one paste #446

Context

When you paste with the terminal's own paste (Cmd+V in most macOS terminals, right-click, middle-click), the text arrives as typed keys: each newline goes through auto-indent, and a long paste becomes many undo steps. Terminal.Gui 2.4+ turns on bracketed paste and raises a Paste event with the whole block. This task puts that block through the same paste Ctrl+V uses. Needs #442, which moves TuiCode to Terminal.Gui 2.5. Part of #40.

Acceptance criteria

• Pasting an indented block with the terminal's paste keeps its indentation exactly: no extra indent added to each line.
• One Ctrl+Z removes the whole paste.
• With several carets, a terminal paste goes in at every caret the way Ctrl+V does today.
• Pasting over a selection replaces it.
• Over SSH, the terminal's paste brings the laptop's clipboard into the remote TuiCode.
• Pasting into the Find field or another text field inserts the text there.
• Typing, including auto-indent on Enter, works as before.

Tests

• A paste event with multi-line, indented, CRLF and tab text inserts it verbatim, as one undo step.
• Multi-caret and replace-selection paths share Ctrl+V's behaviour.
• Paste routed to the focused view: editor, Find field, a dialog's text field.

Out of scope

• The Terminal.Gui upgrade itself (Move TuiCode to Terminal.Gui 2.5 and MentalDesk.Tui 0.2.0 #442).
• Windows' windows driver, which doesn't read VT input; paste there stays as today.
• Changing the terminal integrations' Cmd+V mapping (Cmd+V in the terminal integrations pastes the laptop's clipboard over SSH #447).
• Reading the clipboard with OSC 52.