feat(antigravity): comprehensive enhancements - model mapping, rate limiting, scheduling & ops

Key changes:
- Upgrade model mapping: Opus 4.5 → Opus 4.6-thinking with precise matching
- Unified rate limiting: scope-level → model-level with Redis snapshot sync
- Load-balanced scheduling by call count with smart retry mechanism
- Force cache billing support
- Model identity injection in prompts with leak prevention
- Thinking mode auto-handling (max_tokens/budget_tokens fix)
- Frontend: whitelist mode toggle, model mapping validation, status indicators
- Gemini session fallback with Redis Trie O(L) matching
- Ops: enhanced concurrency monitoring, account availability, retry logic
- Migration scripts: 049-051 for model mapping unification

backend/internal/service/account.go

@@ -3,9 +3,12 @@ package service
 
 import (
 	"encoding/json"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/domain"
 )
 
 type Account struct {
@@ -347,10 +350,18 @@ func parseTempUnschedInt(value any) int {
 
 func (a *Account) GetModelMapping() map[string]string {
 	if a.Credentials == nil {
+		// Antigravity 平台使用默认映射
+		if a.Platform == domain.PlatformAntigravity {
+			return domain.DefaultAntigravityModelMapping
+		}
 		return nil
 	}
 	raw, ok := a.Credentials["model_mapping"]
 	if !ok || raw == nil {
+		// Antigravity 平台使用默认映射
+		if a.Platform == domain.PlatformAntigravity {
+			return domain.DefaultAntigravityModelMapping
+		}
 		return nil
 	}
 	if m, ok := raw.(map[string]any); ok {
@@ -364,27 +375,46 @@ func (a *Account) GetModelMapping() map[string]string {
 			return result
 		}
 	}
+	// Antigravity 平台使用默认映射
+	if a.Platform == domain.PlatformAntigravity {
+		return domain.DefaultAntigravityModelMapping
+	}
 	return nil
 }
 
+// IsModelSupported 检查模型是否在 model_mapping 中（支持通配符）
+// 如果未配置 mapping，返回 true（允许所有模型）
 func (a *Account) IsModelSupported(requestedModel string) bool {
 	mapping := a.GetModelMapping()
 	if len(mapping) == 0 {
+		return true // 无映射 = 允许所有
+	}
+	// 精确匹配
+	if _, exists := mapping[requestedModel]; exists {
 		return true
 	}
-	_, exists := mapping[requestedModel]
-	return exists
+	// 通配符匹配
+	for pattern := range mapping {
+		if matchWildcard(pattern, requestedModel) {
+			return true
+		}
+	}
+	return false
 }
 
+// GetMappedModel 获取映射后的模型名（支持通配符，最长优先匹配）
+// 如果未配置 mapping，返回原始模型名
 func (a *Account) GetMappedModel(requestedModel string) string {
 	mapping := a.GetModelMapping()
 	if len(mapping) == 0 {
 		return requestedModel
 	}
+	// 精确匹配优先
 	if mappedModel, exists := mapping[requestedModel]; exists {
 		return mappedModel
 	}
-	return requestedModel
+	// 通配符匹配（最长优先）
+	return matchWildcardMapping(mapping, requestedModel)
 }
 
 func (a *Account) GetBaseURL() string {
@@ -426,6 +456,53 @@ func (a *Account) GetClaudeUserID() string {
 	return ""
 }
 
+// matchAntigravityWildcard 通配符匹配（仅支持末尾 *）
+// 用于 model_mapping 的通配符匹配
+func matchAntigravityWildcard(pattern, str string) bool {
+	if strings.HasSuffix(pattern, "*") {
+		prefix := pattern[:len(pattern)-1]
+		return strings.HasPrefix(str, prefix)
+	}
+	return pattern == str
+}
+
+// matchWildcard 通用通配符匹配（仅支持末尾 *）
+// 复用 Antigravity 的通配符逻辑，供其他平台使用
+func matchWildcard(pattern, str string) bool {
+	return matchAntigravityWildcard(pattern, str)
+}
+
+// matchWildcardMapping 通配符映射匹配（最长优先）
+// 如果没有匹配，返回原始字符串
+func matchWildcardMapping(mapping map[string]string, requestedModel string) string {
+	// 收集所有匹配的 pattern，按长度降序排序（最长优先）
+	type patternMatch struct {
+		pattern string
+		target  string
+	}
+	var matches []patternMatch
+
+	for pattern, target := range mapping {
+		if matchWildcard(pattern, requestedModel) {
+			matches = append(matches, patternMatch{pattern, target})
+		}
+	}
+
+	if len(matches) == 0 {
+		return requestedModel // 无匹配，返回原始模型名
+	}
+
+	// 按 pattern 长度降序排序
+	sort.Slice(matches, func(i, j int) bool {
+		if len(matches[i].pattern) != len(matches[j].pattern) {
+			return len(matches[i].pattern) > len(matches[j].pattern)
+		}
+		return matches[i].pattern < matches[j].pattern
+	})
+
+	return matches[0].target
+}
+
 func (a *Account) IsCustomErrorCodesEnabled() bool {
 	if a.Type != AccountTypeAPIKey || a.Credentials == nil {
 		return false