refactor: split glm.c into colibri.c + 4 header modules

Rename glm.c → colibri.c and extract four self-contained modules
into header-only files (same pattern as st.h/tier.h/grammar.h):

  quant.h      (672 lines) — SIMD matmul kernels, quantization
  sample.h     (143 lines) — RNG, top-p sampling, stop-set
  kv_persist.h (121 lines) — .coli_kv disk persistence
  telemetry.h  (189 lines) — dashboard protocol, stats, usage

Main engine file shrinks from 6588 to 5396 lines (−18%).

Build system: primary target is now colibri$(EXE); `make glm`
remains as a phony alias for backward compat. CI, setup.sh,
coli CLI, and all 10 test files that include the engine are
updated. make check passes (C + Python, 73 tests, zero warnings).

c/tests/test_i4_grouped.c

@@ -18,7 +18,7 @@
  * index, a wrong group boundary or a swapped nibble cannot hide under it —
  * those are O(1) relative errors, not O(1e-6). */
 #define main coli_glm_main_unused
-#include "../glm.c"
+#include "../colibri.c"
 #undef main
 
 static uint32_t rng_state=0xC0FFEEu;