Add Meson/Ninja build system and update README

[Knogle]

Motivation

• Replace the Autotools-based build with a Meson/Ninja build to modernize and simplify the project build flow.
• Provide an explicit, reproducible Meson configuration that performs dependency/header detection, generates config.h, and exposes formatting/check-format targets.

Description

• Added meson.build that declares the nwipe project, probes dependencies (ncurses, panel, libconfig, libparted, threads), detects ncurses/panel header locations, generates config.h via configure_file, and sets -DHAVE_CONFIG_H for the build.
• Enumerated all source files, added include directories, created the nwipe executable target with installation and added install_man('man/nwipe.8').
• Added format and check-format run targets, with check-format running clang-format and git diff --exit-code to detect formatting changes.
• Removed Autotools artifacts (autogen.sh, configure.ac, Makefile.am, src/Makefile.am, man/Makefile.am) and updated README.md to document Meson/Ninja prerequisites and build/install/formatting instructions (including the automated build script example).

Testing

• Tried meson setup build in the environment but it failed because meson is not installed, so the build could not be completed.
• Attempted to install meson via python3 -m pip install --user meson ninja but the installation failed due to network/proxy restrictions, so no further automated tests were executed.

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Codex Task