feat(auth,prompt-rule): add password change with session revocation and scope prompt rules by brand

Add self-service password change that re-hashes the credential and bumps a
per-user session version so all existing access/refresh tokens are rejected.
Session version is tracked in Redis with an in-memory fallback and enforced in
middleware and refresh.

Scope prompt rules and rule groups to a brand: new brand_id column (migrated to
a "未归属" fallback brand for existing rows), brand-filtered queries/indexes, and
brand-aware admin-web tabs.

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

server/internal/tenant/transport/router.go

@@ -29,6 +29,7 @@ func RegisterRoutes(app *bootstrap.App) {
 	protected.Use(middleware.BrandScope(app.DB))
 
 	protected.GET("/auth/me", authHandler.Me)
+	protected.POST("/auth/password", authHandler.ChangePassword)
 	protected.POST("/auth/logout", authHandler.Logout)
 
 	desktopClientHandler := NewDesktopClientHandler(app)
@@ -229,6 +230,7 @@ func RegisterRoutes(app *bootstrap.App) {
 
 	// Prompt Rules
 	promptRules := tenantProtected.Group("/prompt-rules")
+	promptRules.Use(middleware.RequireCurrentBrand())
 	prHandler := NewPromptRuleHandler(app)
 	promptRules.GET("", prHandler.List)
 	promptRules.GET("/simple", prHandler.ListSimple)