feat(server): hot-reload config store and reloadable infra clients

- Replace single Load() with a watching Store that re-reads config files
  (and config.local.yaml) and fans out a ReloadEvent with a per-field diff
  so consumers can decide whether the change is hot-applicable or requires
  a process restart.
- Wrap llm, retrieval, vector store, and object storage clients in
  Reloadable* shells so the bootstrap can swap their underlying impls when
  config changes without re-instantiating handlers.
- Make jwt.Manager and ops TokenIssuer mutable under a lock so secrets and
  TTLs can be rotated live; thread default plan code through a setter on
  the ops AdminUserService.
- Wire ConfigStore through bootstrap and every cmd/main.go, scheduler /
  worker / tenant-api / ops-api start the watcher; services and handlers
  take a config.Provider so they always read current values for things
  like generation.stream_enabled, scheduler dispatch, retrieval, etc.
- Switch shared/config decoding off viper to a Kratos-derived runtime
  package so env placeholders (\${VAR:default}) resolve consistently and
  the same source machinery powers both the loader and the watcher.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/ops/app/admin_user.go

@@ -6,6 +6,7 @@ import (
 	"net/mail"
 	"regexp"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/jackc/pgx/v5/pgconn"
@@ -35,6 +36,7 @@ var phonePattern = regexp.MustCompile(`^\+?[0-9]{6,20}$`)
 type AdminUserService struct {
 	users           *repository.AdminUserRepository
 	audits          *AuditService
+	configMu        sync.RWMutex
 	defaultPlanCode string
 }
 
@@ -50,6 +52,31 @@ func NewAdminUserService(users *repository.AdminUserRepository, audits *AuditSer
 	}
 }
 
+func (s *AdminUserService) UpdateDefaultPlanCode(defaultPlanCode string) {
+	if s == nil {
+		return
+	}
+	defaultPlanCode = strings.TrimSpace(defaultPlanCode)
+	if defaultPlanCode == "" {
+		defaultPlanCode = "free"
+	}
+	s.configMu.Lock()
+	s.defaultPlanCode = defaultPlanCode
+	s.configMu.Unlock()
+}
+
+func (s *AdminUserService) currentDefaultPlanCode() string {
+	if s == nil {
+		return "free"
+	}
+	s.configMu.RLock()
+	defer s.configMu.RUnlock()
+	if strings.TrimSpace(s.defaultPlanCode) == "" {
+		return "free"
+	}
+	return s.defaultPlanCode
+}
+
 type AdminUserView struct {
 	ID                 int64      `json:"id"`
 	Email              *string    `json:"email"`
@@ -295,7 +322,7 @@ func (s *AdminUserService) Create(ctx context.Context, actor *Actor, in CreateAd
 	}
 	planCode := strings.TrimSpace(in.PlanCode)
 	if planCode == "" {
-		planCode = s.defaultPlanCode
+		planCode = s.currentDefaultPlanCode()
 	}
 	role := strings.TrimSpace(in.Role)
 	if role == "" {

server/internal/ops/app/auth.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/golang-jwt/jwt/v5"
@@ -26,15 +27,31 @@ type OperatorClaims struct {
 }
 
 type TokenIssuer struct {
+	mu        sync.RWMutex
 	secret    []byte
 	accessTTL time.Duration
 }
 
 func NewTokenIssuer(secret string, accessTTL time.Duration) *TokenIssuer {
-	return &TokenIssuer{secret: []byte(secret), accessTTL: accessTTL}
+	issuer := &TokenIssuer{}
+	issuer.Update(secret, accessTTL)
+	return issuer
 }
 
-func (t *TokenIssuer) AccessTTL() time.Duration { return t.accessTTL }
+func (t *TokenIssuer) Update(secret string, accessTTL time.Duration) {
+	if t == nil {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.secret = []byte(secret)
+	t.accessTTL = accessTTL
+}
+
+func (t *TokenIssuer) AccessTTL() time.Duration {
+	_, accessTTL := t.snapshot()
+	return accessTTL
+}
 
 type IssuedToken struct {
 	AccessToken string
@@ -42,8 +59,9 @@ type IssuedToken struct {
 }
 
 func (t *TokenIssuer) Issue(operator *domain.OperatorAccount) (*IssuedToken, error) {
+	secret, accessTTL := t.snapshot()
 	now := time.Now()
-	exp := now.Add(t.accessTTL)
+	exp := now.Add(accessTTL)
 	claims := OperatorClaims{
 		OperatorID:  operator.ID,
 		Username:    operator.Username,
@@ -56,7 +74,7 @@ func (t *TokenIssuer) Issue(operator *domain.OperatorAccount) (*IssuedToken, err
 			ExpiresAt: jwt.NewNumericDate(exp),
 		},
 	}
-	signed, err := jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString(t.secret)
+	signed, err := jwt.NewWithClaims(jwt.SigningMethodHS256, claims).SignedString(secret)
 	if err != nil {
 		return nil, fmt.Errorf("sign ops token: %w", err)
 	}
@@ -64,11 +82,12 @@ func (t *TokenIssuer) Issue(operator *domain.OperatorAccount) (*IssuedToken, err
 }
 
 func (t *TokenIssuer) Parse(raw string) (*OperatorClaims, error) {
+	secret, _ := t.snapshot()
 	token, err := jwt.ParseWithClaims(raw, &OperatorClaims{}, func(tok *jwt.Token) (any, error) {
 		if _, ok := tok.Method.(*jwt.SigningMethodHMAC); !ok {
 			return nil, fmt.Errorf("unexpected signing method: %v", tok.Header["alg"])
 		}
-		return t.secret, nil
+		return secret, nil
 	})
 	if err != nil {
 		return nil, err
@@ -83,6 +102,16 @@ func (t *TokenIssuer) Parse(raw string) (*OperatorClaims, error) {
 	return claims, nil
 }
 
+func (t *TokenIssuer) snapshot() ([]byte, time.Duration) {
+	if t == nil {
+		return nil, 0
+	}
+	t.mu.RLock()
+	defer t.mu.RUnlock()
+	secret := append([]byte(nil), t.secret...)
+	return secret, t.accessTTL
+}
+
 type AuthService struct {
 	accounts *repository.AccountRepository
 	audits   *AuditService