Prepare v0.1.0 release

[Lay007]

Prepare the first public release for the DSP showcase.

Release checklist:

• docs/release-checklist.md

Acceptance criteria:

• release notes summarize implemented DSP modules;
• CI is green on Linux and Windows;
• generated benchmark artifacts are available;
• README build commands are verified;
• archive/tag name follows v0.1.0.

Suggested scope:

• FIR design and convolution;
• FFT overlap-save convolution;
• Goertzel detection;
• GCC-PHAT delay estimation;
• rational resampling;
• benchmark report and generated plots.