fix(toolcall): fix deepseek function calling bug and add json repair

- Fix: Expand stream sieve keywords to support function.name: and [TOOL_CALL_HISTORY]

- Fix: Add repairInvalidJSONBackslashes to handle unescaped backslashes in Windows paths

- Sync: Update JS stream sieve to match Go implementation

- Test: Add unit tests for backslash repair and deepseek format parsing

- Tool: Move repair json test tool to tests/repair_json_tool.go

tests/repair_json_tool.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+func repairInvalidJSONBackslashes(s string) string {
+	if !strings.Contains(s, "\\") {
+		return s
+	}
+	var out strings.Builder
+	out.Grow(len(s) + 10)
+	runes := []rune(s)
+	for i := 0; i < len(runes); i++ {
+		if runes[i] == '\\' {
+			if i+1 < len(runes) {
+				next := runes[i+1]
+				switch next {
+				case '"', '\\', '/', 'b', 'f', 'n', 'r', 't':
+					out.WriteRune('\\')
+					out.WriteRune(next)
+					i++
+					continue
+				case 'u':
+					if i+5 < len(runes) {
+						isHex := true
+						for j := 1; j <= 4; j++ {
+							r := runes[i+1+j]
+							if !((r >= '0' && r <= '9') || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F')) {
+								isHex = false
+								break
+							}
+						}
+						if isHex {
+							out.WriteRune('\\')
+							out.WriteRune('u')
+							for j := 1; j <= 4; j++ {
+								out.WriteRune(runes[i+1+j])
+							}
+							i += 5
+							continue
+						}
+					}
+				}
+			}
+			// Not a valid escape sequence, double it
+			out.WriteString("\\\\")
+		} else {
+			out.WriteRune(runes[i])
+		}
+	}
+	return out.String()
+}
+
+func main() {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{`{"path": "C:\Users\name"}`, `{"path": "C:\\Users\\name"}`},
+		{`{"cmd": "cd D:\git_codes"}`, `{"cmd": "cd D:\\git_codes"}`},
+		{`{"text": "line1\nline2"}`, `{"text": "line1\nline2"}`},
+		{`{"path": "D:\\back\\slash"}`, `{"path": "D:\\back\\slash"}`},
+		{`{"unicode": "\u2705"}`, `{"unicode": "\u2705"}`},
+		{`{"invalid_u": "\u123"}`, `{"invalid_u": "\\u123"}`},
+	}
+
+	for _, tt := range tests {
+		got := repairInvalidJSONBackslashes(tt.input)
+		if got != tt.expected {
+			fmt.Printf("FAIL: input=%s\n  got=%s\n  exp=%s\n", tt.input, got, tt.expected)
+		} else {
+			fmt.Printf("PASS: input=%s\n", tt.input)
+		}
+	}
+}