vibe code the initial impl

main/matcher.h

@@ -0,0 +1,18 @@
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+#include "esp_err.h"
+#include "feature_params.h"
+
+typedef enum { TPL_NONE = 0, TPL_NVS, TPL_BUILTIN } tpl_source_t;
+
+esp_err_t matcher_init(void);   // priority: NVS-learned > compiled-in template.h > none
+bool matcher_has_template(void);
+tpl_source_t matcher_source(void);
+const char *matcher_source_name(void);
+uint32_t matcher_frame_count(void);
+bool matcher_suggested_threshold(float *thr);   // from template.h, if the tool computed one
+float matcher_score(const float fp[NUM_BANDS]); // cosine vs active template (0 if none)
+void matcher_get_template(float out[NUM_BANDS]);
+esp_err_t matcher_set_template(const float fp[NUM_BANDS], uint32_t frame_count);   // -> NVS, source = NVS
+esp_err_t matcher_reset(void);                  // erase NVS template, fall back to built-in