feat(version): 第18条 显示版本与内部版本解耦（V/A 双系）

- config 新增 displayVersion 注入变量（默认 1.0.0）：GetDisplayVersion/
  GetMasterDisplayVersion(V)/GetAgentDisplayVersion(A)，以后升版只改注入值
- ParseDisplayVersion/CompareDisplayVersion：三段数值比较，个位进位规则
  (1.0.9<1.1.0) 天然成立；不可解析（dev 标签/3.7.0-agent.1）返回 ok=false
- 显示位切换：dist 注入 X_UI_CUR_VER、-v、TG 报告 → V 系；
  agent 遥测 agentVersion → A 系；节点行 A 系原样显示、老 agent 沿用
  "agent " 前缀兼容
- 内部流不动：GetBaseVersion/GetPanelVersion 及其比较/订阅/远端状态
  消费方保持原样，传统节点更新判定与徽标行为不变

internal/config/config.go

@@ -35,6 +35,13 @@ var (
 	buildCommit  string
 	buildDate    string
 	buildVersion string
+	// displayVersion is this fork's own user-facing release number ("1.0.0"
+	// in "V1.0.0" / "A1.0.0"), injected via `-ldflags -X` by release builds.
+	// It is deliberately separate from buildVersion (the upstream-shaped
+	// internal version): display surfaces (panel header, node list, agent
+	// telemetry) read the V/A display version, while internal comparisons
+	// and advertisements keep using GetBaseVersion/GetPanelVersion.
+	displayVersion string
 )
 
 // LogLevel represents the logging level for the application.
@@ -103,6 +110,96 @@ func GetPanelVersion() string {
 	return "dev+" + commit
 }
 
+// defaultDisplayVersion is the display version reported when a build does
+// not inject one (plain `go build` / `go run`).
+const defaultDisplayVersion = "1.0.0"
+
+// GetDisplayVersion returns the bare numeric display version ("1.0.0"):
+// the injected display version when the build provided one, else the
+// default. Display versions advance in single-digit carry steps
+// (1.0.9 -> 1.1.0 -> ... -> 1.9.9 -> 2.0.0); each segment stays 0-9.
+func GetDisplayVersion() string {
+	if v := strings.TrimSpace(displayVersion); v != "" {
+		return v
+	}
+	return defaultDisplayVersion
+}
+
+// GetMasterDisplayVersion is the master's display version ("V1.0.0"),
+// shown in the panel's version slot.
+func GetMasterDisplayVersion() string {
+	return "V" + GetDisplayVersion()
+}
+
+// GetAgentDisplayVersion is the agent's display version ("A1.0.0"),
+// reported in agent telemetry and shown on agent node rows.
+func GetAgentDisplayVersion() string {
+	return "A" + GetDisplayVersion()
+}
+
+// ParseDisplayVersion parses a display version into its three numeric
+// segments. It accepts the bare form ("1.0.0") and the letter-prefixed
+// display forms ("V1.0.0", "A1.0.0", "v1.0.0"). Anything else — dev labels,
+// suffixed builds like "3.7.0-agent.1", wrong segment counts, non-numeric
+// segments — reports ok=false so callers can fall back instead of guessing.
+func ParseDisplayVersion(s string) (parts [3]int, ok bool) {
+	s = strings.TrimSpace(s)
+	if parsed, good := parseDisplayParts(s); good {
+		return parsed, true
+	}
+	// Retry once without a single leading display letter (V/A, any case).
+	if len(s) > 1 && (s[0] == 'V' || s[0] == 'v' || s[0] == 'A' || s[0] == 'a') {
+		if parsed, good := parseDisplayParts(s[1:]); good {
+			return parsed, true
+		}
+	}
+	return [3]int{}, false
+}
+
+func parseDisplayParts(s string) ([3]int, bool) {
+	var parts [3]int
+	segs := strings.Split(s, ".")
+	if len(segs) != 3 {
+		return parts, false
+	}
+	for i, seg := range segs {
+		if seg == "" {
+			return parts, false
+		}
+		for _, r := range seg {
+			if r < '0' || r > '9' {
+				return parts, false
+			}
+		}
+		n, err := strconv.Atoi(seg)
+		if err != nil {
+			return parts, false
+		}
+		parts[i] = n
+	}
+	return parts, true
+}
+
+// CompareDisplayVersion compares two display versions segment by segment
+// (numeric, so the single-digit carry rule 1.0.9 < 1.1.0 holds naturally).
+// ok=false when either side is not a parseable display version.
+func CompareDisplayVersion(a, b string) (cmp int, ok bool) {
+	pa, okA := ParseDisplayVersion(a)
+	pb, okB := ParseDisplayVersion(b)
+	if !okA || !okB {
+		return 0, false
+	}
+	for i := range 3 {
+		if pa[i] != pb[i] {
+			if pa[i] < pb[i] {
+				return -1, true
+			}
+			return 1, true
+		}
+	}
+	return 0, true
+}
+
 // GetLogLevel returns the current logging level based on environment variables or defaults to Info.
 func GetLogLevel() LogLevel {
 	if IsDebug() {