Add module READMEs, .gitignore, and remove Bin/ from tracking

Add README.md for each library module documenting API, platform
backends, and usage. Add .gitignore for build artifacts. Remove
pre-built binaries from version control.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

libsst-random/README.md

@@ -0,0 +1,36 @@
+# libsst-random
+
+Pseudorandom number generation and simplex noise in C.
+
+## PRNG algorithms
+
+| Type | Enum | State size |
+|---|---|---|
+| Mersenne Twister | `SST_PRNG_MERSENNE` | 624 x 32-bit |
+| CMWC | `SST_PRNG_CMWC` | 4096 x 32-bit |
+| SmallPRNG | `SST_PRNG_SMALLPRNG` | 4 x 32-bit |
+
+### Generic API
+
+```c
+SST_PRNG rng = SST_Random_CreatePRNGFromSeed(SST_PRNG_MERSENNE, 42);
+float  f = SST_Random_GetPRNGFloat(rng, 0.0f, 1.0f);
+int    i = SST_Random_GetPRNGInt(rng, 0, 100);
+SST_Random_DestroyPRNG(rng);
+```
+
+Each algorithm also has direct-access functions
+(`SST_Random_*SmallPRNG*`, `SST_Random_*CMWC*`).
+Array-fill variants are provided for batch generation.
+
+## Simplex noise
+
+1D through 4D simplex noise, returning values in [-1, 1]:
+
+- `SST_Random_MapSimplexNoise{1,2,3,4}D()`
+- Array variants: `SST_Random_MapSimplexNoise{1,2,3,4}DFromArray()`
+
+## C++ wrappers
+
+- `ZRandomGenerator` -- RAII wrapper with Gaussian distribution support
+- `ZSimplexNoise` -- RAII wrapper with `noise1`/`noise2`/`noise3`/`noise4`