feat: add PuLID-Flux identity-injection support (#1595)

include/stable-diffusion.h

@@ -195,6 +195,16 @@ typedef struct {
     const sd_embedding_t* embeddings;
     uint32_t embedding_count;
     const char* photo_maker_path;
+    /**
+     * Path to pulid_flux_v0.9.1.safetensors (the PuLID identity-injection
+     * cross-attention weights). When set together with sd_img_gen_params_t.
+     * pulid_params.id_embedding_path, the Flux diffusion model performs PuLID
+     * cross-attention injection during the denoise loop. Loaded once with
+     * the model; the embedding is per-generation. Currently only meaningful
+     * for Flux (depth=19 double, 38 single blocks); silently ignored for
+     * other model versions.
+     */
+    const char* pulid_weights_path;
     const char* tensor_type_rules;
     int n_threads;
     enum sd_type_t wtype;
@@ -272,6 +282,25 @@ typedef struct {
     float style_strength;
 } sd_pm_params_t;  // photo maker
 
+/**
+ * PuLID-Flux identity preservation params.
+ *
+ * Unlike PhotoMaker (which extracts the ID embedding inside the inference
+ * process from a directory of images), PuLID's ID extraction is a heavy
+ * Python-only stack (insightface ArcFace + EVA-CLIP-L + IDFormer). To stay
+ * cross-vendor in C++/Vulkan, sd.cpp consumes a precomputed binary file
+ * produced by an external tool (runtime-scripts/pulid_extract_id.py in the
+ * Cloudhands client tree).
+ *
+ * Format: a gguf container with a single tensor "pulid_id" of shape
+ * [token_dim, num_tokens] (ggml order; typically [2048, 32]) in F16/F32/BF16.
+ * Loaded with the standard gguf reader; see docs/pulid.md.
+ */
+typedef struct {
+    const char* id_embedding_path;  // path to .pulidembd file produced by pulid_extract_id.py
+    float id_weight;                // strength of the ID injection; typical 0.7-1.2, default 1.0
+} sd_pulid_params_t;
+
 enum sd_cache_mode_t {
     SD_CACHE_DISABLED = 0,
     SD_CACHE_EASYCACHE,
@@ -364,6 +393,7 @@ typedef struct {
     sd_image_t control_image;
     float control_strength;
     sd_pm_params_t pm_params;
+    sd_pulid_params_t pulid_params;
     sd_tiling_params_t vae_tiling_params;
     sd_cache_params_t cache;
     sd_hires_params_t hires;