Fix: Resolve Go and Flutter compilation errors

Go backend:
- Fix WOPI models file (remove duplicate package declaration and syntax errors)
- Add GetOrgMember method to database as alias for GetUserMembership
- Add UpdateFileSize method to database
- Remove unused net/url import from wopi_handlers.go
- Fix field names in WOPI struct initializers (match JSON tags)

Flutter frontend:
- Remove webview_flutter import (use simpler placeholder for now)
- Fix _createWOPISession to safely access SessionBloc state
- Replace WebViewController usage with placeholder UI
- Remove unused _generateRandomHex methods from login/signup forms
- Add missing mimeType parameter to DocumentCapabilities in mock repository
- Remove unused local variables in file_browser_bloc

go_cloud/internal/models/wopi.go

@@ -1,5 +1,4 @@
 package models
-package models
 
 import "time"
 
@@ -7,16 +6,70 @@ import "time"
 // Reference: https://docs.microsoft.com/en-us/openspecs/office_protocols/ms-wopi/4b8ffc3f-e8a6-4169-8c4e-34924ac6ae2f
 type WOPICheckFileInfoResponse struct {
 	BaseFileName                    string    `json:"BaseFileName"`
-	Size                           int64     `json:"Size"`
-	Version                        string    `json:"Version"`
-	OwnerId                        string    `json:"OwnerId"`
-	UserId                         string    `json:"UserId"`
-	UserFriendlyName               string    `json:"UserFriendlyName"`
-	UserCanWrite                   bool      `json:"UserCanWrite"`
-	UserCanRename                  bool      `json:"UserCanRename"`
-	UserCanNotWriteRelative        bool      `json:"UserCanNotWriteRelative"`
-	ReadOnly                       bool      `json:"ReadOnly"`
-	RestrictedWebViewOnly          bool      `json:"RestrictedWebViewOnly"`
+	Size                            int64     `json:"Size"`
+	Version                         string    `json:"Version"`
+	OwnerId                         string    `json:"OwnerId"`
+	UserId                          string    `json:"UserId"`
+	UserFriendlyName                string    `json:"UserFriendlyName"`
+	UserCanWrite                    bool      `json:"UserCanWrite"`
+	UserCanRename                   bool      `json:"UserCanRename"`
+	UserCanNotWriteRelative         bool      `json:"UserCanNotWriteRelative"`
+	ReadOnly                        bool      `json:"ReadOnly"`
+	RestrictedWebViewOnly           bool      `json:"RestrictedWebViewOnly"`
+	UserCanCreateRelativeToFolder   bool      `json:"UserCanCreateRelativeToFolder"`
+	EnableOwnerTermination          bool      `json:"EnableOwnerTermination"`
+	SupportsUpdate                  bool      `json:"SupportsUpdate"`
+	SupportsCobalt                  bool      `json:"SupportsCobalt"`
+	SupportsLocks                   bool      `json:"SupportsLocks"`
+	SupportsExtendedLockLength      bool      `json:"SupportsExtendedLockLength"`
+	SupportsGetLock                 bool      `json:"SupportsGetLock"`
+	SupportsDelete                  bool      `json:"SupportsDelete"`
+	SupportsRename                  bool      `json:"SupportsRename"`
+	SupportsRenameRelativeToFolder  bool      `json:"SupportsRenameRelativeToFolder"`
+	SupportsFolders                 bool      `json:"SupportsFolders"`
+	SupportsScenarios               []string  `json:"SupportsScenarios"`
+	LastModifiedTime                string    `json:"LastModifiedTime"`
+	IsAnonymousUser                 bool      `json:"IsAnonymousUser"`
+	TimeZone                        string    `json:"TimeZone"`
+	CloseUrl                        string    `json:"CloseUrl,omitempty"`
+	EditUrl                         string    `json:"EditUrl,omitempty"`
+	ViewUrl                         string    `json:"ViewUrl,omitempty"`
+	FileSharingUrl                  string    `json:"FileSharingUrl,omitempty"`
+	DownloadUrl                     string    `json:"DownloadUrl,omitempty"`
+}
+
+// WOPIPutFileResponse represents the response to WOPI PutFile request
+type WOPIPutFileResponse struct {
+	ItemVersion string `json:"ItemVersion"`
+}
+
+// WOPILockInfo represents information about a file lock
+type WOPILockInfo struct {
+	FileID    string    `json:"file_id"`
+	UserID    string    `json:"user_id"`
+	LockID    string    `json:"lock_id"`
+	CreatedAt time.Time `json:"created_at"`
+	ExpiresAt time.Time `json:"expires_at"`
+}
+
+// WOPIAccessTokenRequest represents a request to get WOPI access token
+type WOPIAccessTokenRequest struct {
+	FileID string `json:"file_id"`
+}
+
+// WOPIAccessTokenResponse represents a response with WOPI access token
+type WOPIAccessTokenResponse struct {
+	AccessToken      string `json:"access_token"`
+	AccessTokenTTL   int64  `json:"access_token_ttl"`
+	BootstrapperUrl  string `json:"bootstrapper_url,omitempty"`
+	ClosePostMessage bool   `json:"close_post_message"`
+}
+
+// WOPISessionResponse represents a response for creating a WOPI session
+type WOPISessionResponse struct {
+	WOPISrc     string `json:"wopi_src"`
+	AccessToken string `json:"access_token"`
+}