Implement complete Organizations feature with RBAC

- Add owner/admin/member roles with proper permissions
- Implement invite links and join requests system
- Add organization settings dialog with member management
- Create database migrations for invitations and invite links
- Update backend API with org management endpoints
- Fix compilation errors and audit logging
- Update frontend models and API integration

go_cloud/migrations/0005_org_invitations.sql

@@ -0,0 +1,29 @@
+-- Add invitations and join_requests tables for organization management
+
+CREATE TABLE invitations (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    org_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    invited_by UUID NOT NULL REFERENCES users(id),
+    username TEXT NOT NULL, -- username of the invited user
+    role TEXT NOT NULL CHECK (role IN ('owner', 'admin', 'member')),
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    expires_at TIMESTAMP WITH TIME ZONE DEFAULT (NOW() + INTERVAL '7 days'),
+    accepted_at TIMESTAMP WITH TIME ZONE,
+    UNIQUE(org_id, username) -- prevent duplicate invites for same user in org
+);
+
+CREATE TABLE join_requests (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    org_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL REFERENCES users(id),
+    invite_token TEXT, -- optional, if from invite link
+    requested_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    status TEXT NOT NULL DEFAULT 'pending' CHECK (status IN ('pending', 'accepted', 'rejected')),
+    UNIQUE(org_id, user_id) -- prevent duplicate requests
+);
+
+-- Index for faster lookups
+CREATE INDEX idx_invitations_org_id ON invitations(org_id);
+CREATE INDEX idx_invitations_username ON invitations(username);
+CREATE INDEX idx_join_requests_org_id ON join_requests(org_id);
+CREATE INDEX idx_join_requests_user_id ON join_requests(user_id);