Add Windows resize key support

[prateekbhujel]

This follows up on the v0.4.0 review with the one remaining real runtime gap and clearer docs.

Changes:

• Map Windows ReadConsoleInputW() WINDOW_BUFFER_SIZE_EVENT to Terminal\Key::Resize.
• Move the README problem statement before the API/install details.
• Document that null sequence timeout uses the default 25ms POSIX sequence timeout.
• Document current key input scope: normalized prompt keys, printable code points, Ctrl bytes, and the F-key/modifier/grapheme limits.
• Prepare patch release metadata as 0.4.1.

Notes:

• CSI guards, ANSI env handling, and raw-mode re-entry were already fixed in v0.4.0; this PR does not duplicate those changes.
• PECL search still shows no terminal package listed; package.xml validates cleanly and remains ready for a PECL submission path.

Local verification:

• git diff --check
• php -l terminal.stub.php examples/basic.php examples/prompt.php examples/doctor.php
• pear package-validate package.xml -> 0 error(s), 0 warning(s)
• /Applications/XAMPP/xamppfiles/bin/phpize
• CFLAGS="-arch x86_64 -Wall -Wextra" LDFLAGS="-arch x86_64" ./configure --with-php-config=/Applications/XAMPP/xamppfiles/bin/php-config --enable-terminal
• make -j$(sysctl -n hw.ncpu)
• make test REPORT_EXIT_STATUS=1 NO_INTERACTION=1 TEST_PHP_EXECUTABLE=/Applications/XAMPP/xamppfiles/bin/php -> 15/15 passed
• doctor example reports version 0.4.1