fix(tui): fix Linux Ctrl+C regression, remove double clipboard write

- Fix critical regression: on Linux, Ctrl+C could not interrupt/clear/exit
  because isAction(key,'c') shadowed the isCtrl block (both resolve to k.ctrl
  on non-macOS). Restructured: isAction block now falls through to interrupt
  logic on non-macOS when no selection exists.
- Remove double pbcopy: ink's copySelection() already calls setClipboard()
  which handles pbcopy+tmux+OSC52. The extra writeClipboardText call in
  useInputHandlers copySelection() was firing pbcopy a second time.
- Remove allowClipboardHotkeys prop from TextInput — every caller passed
  isMac, and TextInput already imports isMac. Eliminated prop-drilling
  through appLayout, maskedPrompt, and prompts.
- Remove dead code: the isCtrl copy paths (lines 277-288) were unreachable
  on any platform after the isAction block changes.
- Simplify textInput Cmd+C: use writeClipboardText directly without the
  redundant OSC52 fallback (this path is macOS-only where pbcopy works).

ui-tui/src/components/maskedPrompt.tsx

@@ -2,7 +2,6 @@ import { Box, Text } from '@hermes/ink'
 import { useState } from 'react'
 
 import type { Theme } from '../theme.js'
-import { isMac } from '../lib/platform.js'
 
 import { TextInput } from './textInput.js'
 
@@ -19,7 +18,7 @@ export function MaskedPrompt({ cols = 80, icon, label, onSubmit, sub, t }: Maske
 
       <Box>
         <Text color={t.color.label}>{'> '}</Text>
-        <TextInput columns={Math.max(20, cols - 6)} allowClipboardHotkeys={isMac} mask="*" onChange={setValue} onSubmit={onSubmit} value={value} />
+        <TextInput columns={Math.max(20, cols - 6)} mask="*" onChange={setValue} onSubmit={onSubmit} value={value} />
       </Box>
     </Box>
   )