优化原生结果编码传输与浏览器缓存，记录八路性能基线

原生结果series通过字节索引直传，C端使用Ryu精确回读编码和64 KiB批量写出；网页采用Float64缓存和CSV工作线程，减少结果处理与保存等待。

补充八路AME曲线核查、全流程分阶段计时、独立编码基准和复现工具，固定后续优化采用修正八路及rtol=1e-8。C写出1.1808→0.1638 s，点击到可查看8.0100→6.9756 s。

验证：最终10项编码专项、29项相关后端回归通过；8份原生结果逐位一致，16次网页结果/CSV/刷新恢复通过。前端构建及缓存/CSV专项在本轮结果处理工作中通过。环境、原始大结果与临时构建不纳入Git。

native/runtime/json_numbers.c

@@ -0,0 +1,83 @@
+#include "json_numbers.h"
+#include "ryu/ryu.h"
+#include <float.h>
+#include <stdint.h>
+#include <string.h>
+
+_Static_assert(sizeof(double)==8 && DBL_MANT_DIG==53 && DBL_MAX_EXP==1024,
+               "Native JSON numbers require IEEE-754 binary64");
+
+int native_json_format_double(char output[NATIVE_JSON_DOUBLE_CAPACITY], double value) {
+    uint64_t bits;
+    memcpy(&bits,&value,sizeof(bits));
+    uint64_t magnitude=bits & UINT64_C(0x7fffffffffffffff);
+    if (magnitude>=UINT64_C(0x7ff0000000000000)) return 0;
+    if (magnitude==0) {
+        if (bits>>63) { memcpy(output,"-0.0",4); return 4; }
+        output[0]='0'; return 1;
+    }
+    int length=d2s_buffered_n(value,output);
+    /* Ryu returns shortest significant digits in scientific notation. Use
+       ordinary notation only when its JSON token is shorter. This moves an
+       exact decimal point; it never recomputes or rounds the floating value. */
+    char digits[17];
+    int negative=output[0]=='-', count=0, pos=negative;
+    while (output[pos]!='E') {
+        if (output[pos]!='.') digits[count++]=output[pos];
+        pos++;
+    }
+    pos++;
+    int exponent_negative=output[pos]=='-';
+    if (exponent_negative) pos++;
+    int exponent=0;
+    while (pos<length) exponent=exponent*10+(output[pos++]-'0');
+    if (exponent_negative) exponent=-exponent;
+    int point=exponent+1;
+    int fixed_length=negative+(point<=0 ? 2-point+count : point>=count ? point : count+1);
+    if (fixed_length>=length) return length;
+    pos=0;
+    if (negative) output[pos++]='-';
+    if (point<=0) {
+        output[pos++]='0'; output[pos++]='.';
+        for (int i=0;i<-point;i++) output[pos++]='0';
+        memcpy(output+pos,digits,(size_t)count); pos+=count;
+    } else {
+        for (int i=0;i<count;i++) {
+            if (i==point) output[pos++]='.';
+            output[pos++]=digits[i];
+        }
+        for (int i=count;i<point;i++) output[pos++]='0';
+    }
+    return pos;
+}
+
+static int write_bytes(FILE *file, const char *data, size_t length) {
+    return fwrite(data,1,length,file)==length && !ferror(file);
+}
+
+int native_json_write_number(FILE *file, double value) {
+    if (!file || ferror(file)) return 0;
+    char text[NATIVE_JSON_DOUBLE_CAPACITY];
+    int length=native_json_format_double(text,value);
+    return length>0 && write_bytes(file,text,(size_t)length);
+}
+
+int native_json_write_array(FILE *file, const double *values, size_t count, size_t stride) {
+    if (!file || ferror(file) || (count && !values)) return 0;
+    if (count>1 && (!stride || stride>(size_t)PTRDIFF_MAX/sizeof(double)/(count-1))) return 0;
+    char buffer[65536];
+    size_t used=1;
+    buffer[0]='[';
+    for (size_t i=0;i<count;i++) {
+        if (used>sizeof(buffer)-NATIVE_JSON_DOUBLE_CAPACITY-2) {
+            if (!write_bytes(file,buffer,used)) return 0;
+            used=0;
+        }
+        if (i) buffer[used++]=',';
+        int length=native_json_format_double(buffer+used,values[i*stride]);
+        if (!length) return 0;
+        used+=(size_t)length;
+    }
+    buffer[used++]=']';
+    return write_bytes(file,buffer,used);
+}