SSH client: a terminal on another machine (#2)

The SSH App opens one session to a shell, over libssh (LibSSH-ESP32 5.10.0)
on mbedTLS. A server is trusted the first time on its fingerprint, and a
changed key is a warning with Cancel selected. The password is typed each
time and kept nowhere; or the device makes itself an Ed25519 key, whose
public half is shown, written to /ssh/id_ed25519.pub and printed by
`ssh status`.

lib/term is the terminal: what a shell, less, top, nano and vim send, with
sixteen colours, scroll regions, the alternate screen and 100 lines of
scrollback. Five text sizes with Ctrl and + or -, from 60x20 to 26x8, told
to the far end. The session goes on when the App is left; SSH shows in the
Status Bar. `ssh user@host` in the Shell opens the App.

Also:
- Keys that aren't characters carry Shift, Ctrl and Alt. The terminal needs
  it, and it makes Ctrl+Fn+up/down in a note and Shift+Tab in Gemini work
  from the real keyboard.
- IRC doesn't try to connect under 60 KB free: started with a session open,
  its TLS handshake took the heap down to 236 bytes.
- libssh's own curve25519 is left out of the build (scripts/libssh_filter.py):
  libsodium's has the same names.

Costs 292 KB of flash and about 50 KB of heap while a session is open; not
started under 75 KB free.

Docs: guide page, how-to, FAQ, home page, Status Bar, SD card folders, the
memory how-to, README, glossary, N1 notes with Q254 to Q266 and the checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/input/src/key_mapper.cpp

@@ -43,6 +43,15 @@ KeyEvent charEvent(uint32_t cp, const RawKeys& keys) {
     return e;
 }
 
+// A key that isn't a character, with what was held: a terminal tells Alt+Enter from Enter (issue #2).
+KeyEvent keyEvent(Key key, const RawKeys& keys) {
+    KeyEvent e = KeyEvent::of(key);
+    e.shift = keys.shift;
+    e.ctrl = keys.ctrl;
+    e.alt = keys.alt;
+    return e;
+}
+
 }  // namespace
 
 std::vector<KeyEvent> KeyMapper::update(const RawKeys& keys) {
@@ -51,9 +60,9 @@ std::vector<KeyEvent> KeyMapper::update(const RawKeys& keys) {
     if (keys.opt && !previous_.opt && keys.chars.empty()) {
         compose_ = compose_ ? 0 : kArmed;  // a second opt cancels
     }
-    if (keys.enter && !previous_.enter) out.push_back(KeyEvent::of(Key::Select));
-    if (keys.del && !previous_.del) out.push_back(KeyEvent::of(Key::Delete));
-    if (keys.tab && !previous_.tab) out.push_back(KeyEvent::of(Key::Tab));
+    if (keys.enter && !previous_.enter) out.push_back(keyEvent(Key::Select, keys));
+    if (keys.del && !previous_.del) out.push_back(keyEvent(Key::Delete, keys));
+    if (keys.tab && !previous_.tab) out.push_back(keyEvent(Key::Tab, keys));
 
     for (char c : keys.chars) {
         bool wasHeld = std::find(previous_.chars.begin(), previous_.chars.end(), c) != previous_.chars.end();
@@ -89,10 +98,10 @@ void KeyMapper::onChar(char c, const RawKeys& keys, std::vector<KeyEvent>& out)
 
     if (keys.fn || !textEntry_) {
         switch (c) {
-            case ';': out.push_back(KeyEvent::of(Key::Up)); return;
-            case '.': out.push_back(KeyEvent::of(Key::Down)); return;
-            case ',': out.push_back(KeyEvent::of(Key::Left)); return;
-            case '/': out.push_back(KeyEvent::of(Key::Right)); return;
+            case ';': out.push_back(keyEvent(Key::Up, keys)); return;
+            case '.': out.push_back(keyEvent(Key::Down, keys)); return;
+            case ',': out.push_back(keyEvent(Key::Left, keys)); return;
+            case '/': out.push_back(keyEvent(Key::Right, keys)); return;
             case '`':
                 if (keys.fn) {
                     out.push_back(KeyEvent::of(Key::Home));
@@ -126,7 +135,7 @@ void KeyMapper::onChar(char c, const RawKeys& keys, std::vector<KeyEvent>& out)
         }
     }
     if (c == '`') {
-        out.push_back(KeyEvent::of(Key::Back));
+        out.push_back(keyEvent(Key::Back, keys));
         return;
     }
     out.push_back(charEvent(static_cast<unsigned char>(c), keys));