fix: buffer write hardening across wolfSSH

[MarkAtwood]

Buffer-write hardening across wolfSSH. Three independent fixes reported by Fenrir static analysis, batched into one PR. Build-verified on Ubuntu 24.04 against wolfSSL --enable-all --enable-ssh (./configure --enable-all && make -j8, exit 0).

• #3446 — examples/portfwd/portfwd.c and examples/client/common.c: clamp passwordSz to sizeof(userPassword) (256) before the memcpy. Without the clamp, a defaultPassword longer than 256 bytes overflows the fixed userPassword buffer. userPassword is a raw password buffer whose length travels in password.passwordSz, so clamping without a NUL terminator is correct.
• #4105 — examples/client/client.c and apps/wolfssh/wolfssh.c: in readPeer()'s Windows branch, WriteFile now writes (DWORD)ret (bytes actually read) instead of the full bufSz, matching the POSIX write(STDOUT_FILENO, buf, ret) sibling. Prevents emitting stale buffer tail on short reads.
• #4106 — src/wolfterm.c cases 'D' and 'E': WS_WRITECONSOLE now writes sizeof("\n") - 1 (1 byte) instead of sizeof("\n") (2 bytes), dropping the stray trailing NUL from the console output.

The #4105 and #4106 sites are under USE_WINDOWS_API (not compiled on Linux); they are source-verified against the working POSIX path. The #3446 sites are compiled and covered by the successful Linux build.

Reported by Fenrir static analysis.

[Copilot]

Pull request overview

This PR hardens several buffer-write sites across wolfSSH (mostly in examples and Windows-only console output paths) to prevent buffer overflows and unintended output of stale/NUL bytes.

Changes:

• Clamp password copy length to the fixed userPassword[256] buffer size before memcpy in example authentication callbacks.
• On Windows, write only the number of bytes actually read (ret) to stdout in readPeer() instead of the full buffer size.
• In Windows console escape-sequence handling, write only the newline character (not the trailing NUL) via WriteConsole.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/wolfterm.c	Avoids writing the trailing NUL when emitting "\n" via WriteConsole in escape-sequence cases.
examples/portfwd/portfwd.c	Clamps passwordSz to prevent overflow when copying defaultPassword into userPassword[256].
examples/client/common.c	Same password-length clamp as port forwarding example to prevent overflow into userPassword[256].
examples/client/client.c	Windows readPeer() now writes only ret bytes to stdout to avoid emitting stale buffer tail.
apps/wolfssh/wolfssh.c	Same Windows readPeer() stdout write-length fix as the client example.

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