fix: replace duplicate libfftw3-dev with libfftw3-bin for SatDump runtime

The FFTW3 dev package was listed twice in the build stage and both
copies were removed during cleanup, taking the runtime .so with them.
Switching the duplicate to libfftw3-bin ensures libfftw3f.so.3 persists.

Fixes #166

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -91,7 +91,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     zlib1g-dev \
     libzmq3-dev \
     libpulse-dev \
-    libfftw3-dev \
+    libfftw3-bin \
     liblapack-dev \
     libglib2.0-dev \
     libxml2-dev \