fix(tui): honor client copy shortcut over ssh

- accept forwarded Cmd+C for selection copy in SSH sessions even when Hermes runs on Linux
- keep local Linux Alt+C from acting as copy and update TUI hotkey hints for remote shells

ui-tui/src/__tests__/platform.test.ts

@@ -31,6 +31,28 @@ describe('platform action modifier', () => {
   })
 })
 
+describe('isCopyShortcut', () => {
+  it('keeps Ctrl+C as the local non-macOS copy chord', async () => {
+    const { isCopyShortcut } = await importPlatform('linux')
+
+    expect(isCopyShortcut({ ctrl: true, meta: false, super: false }, 'c', {})).toBe(true)
+  })
+
+  it('accepts client Cmd+C over SSH even when running on Linux', async () => {
+    const { isCopyShortcut } = await importPlatform('linux')
+    const env = { SSH_CONNECTION: '1 2 3 4' } as NodeJS.ProcessEnv
+
+    expect(isCopyShortcut({ ctrl: false, meta: false, super: true }, 'c', env)).toBe(true)
+    expect(isCopyShortcut({ ctrl: false, meta: true, super: false }, 'c', env)).toBe(true)
+  })
+
+  it('does not treat local Linux Alt+C as copy', async () => {
+    const { isCopyShortcut } = await importPlatform('linux')
+
+    expect(isCopyShortcut({ ctrl: false, meta: true, super: false }, 'c', {})).toBe(false)
+  })
+})
+
 describe('isVoiceToggleKey', () => {
   it('matches raw Ctrl+B on macOS (doc-default across platforms)', async () => {
     const { isVoiceToggleKey } = await importPlatform('darwin')