Phase 8: wire IDCT QPU dispatch through public API

daedalus_ctx now owns a v3d_runner when V3D is available. The
public API's dispatch_vp9_idct8 routes QPU calls through a
new dispatch_idct8_qpu helper that: (1) lazy-creates the cycle 1
v4 pipeline on first use, (2) allocates 3 host-visible SSBOs
per call (coeffs/dst/meta), (3) memcpy host->GPU, (4) dispatch
with the v4 32-blocks-per-WG geometry, (5) memcpy GPU->host.

Per-call alloc is intentional for Phase 8 correctness-first
scope; buffer-pool perf optimization is deferred.

Added daedalus_ctx_create_no_qpu() for fast-path callers that
know they want CPU only.

test_api_idct extended to a 3-mode matrix: CPU forced, QPU
forced, AUTO recipe. All three deliver 4096/4096 bit-exact
on hertz with V3D 7.1.7.0:

  recipe substrate for VP9_IDCT8: 2 (QPU)
  [CPU] 4096/4096 bit-exact
  [QPU] 4096/4096 bit-exact (real QPU dispatch through the API)
  [AUTO] 4096/4096 bit-exact (recipe routes to QPU)

Next Phase 8 sub-step: same wiring pattern for cycle 2 LPF wd=4
and cycle 4 LPF wd=8 (the other two recipe-QPU kernels).
Cycle 3 MC and cycle 5 CDEF only need the dispatch hook
(recipe routes to CPU; QPU stays opportunistic via explicit
override).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -282,6 +282,7 @@ endif()
 
 add_library(daedalus_core STATIC
     src/daedalus_core.c
+    src/v3d_runner.c
     ${FFASM_SOURCES}
     ${FFASM_LPF_SOURCES}
     ${FFASM_MC_SOURCES}
@@ -290,7 +291,12 @@ add_library(daedalus_core STATIC
     ${DAV1D_CDEF_C_SOURCES}
 )
 target_include_directories(daedalus_core PUBLIC include)
+target_include_directories(daedalus_core PRIVATE src)
+target_link_libraries(daedalus_core PUBLIC Vulkan::Vulkan)
 target_compile_options(daedalus_core PRIVATE -O2)
+if (DAEDALUS_BUILD_VULKAN)
+    add_dependencies(daedalus_core daedalus_shaders)
+endif()
 
 add_executable(test_api_idct
     tests/test_api_idct.c