Squashed commit of the following:

commit 1eeea9f83ad9230a5c1f7a75662770eaab0df837
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 21:15:41 2025 +0200

    Disable resuming of old time entries.

commit 3e3ec2f01cb7943622b819a19179388078ae1315
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 20:59:19 2025 +0200

    Refactor db migrations.

commit 15a51a569da36c6b7c9e01ab17b6fdbdee6ad994
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 19:58:04 2025 +0200

    Apply new style for Time Tracking view.

commit 77e5278b303e060d2b03853b06277f8aa567ae68
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 18:06:04 2025 +0200

    Allow direct registrations as a Company.

commit 188a8772757cbef374243d3a5f29e4440ddecabe
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 18:04:45 2025 +0200

    Add email invitation feature.

commit d9ebaa02aa01b518960a20dccdd5a327d82f30c6
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 17:12:32 2025 +0200

    Apply common style for Company, User, Team management pages.

commit 81149caf4d8fc6317e2ab1b4f022b32fc5aa6d22
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 16:44:32 2025 +0200

    Move export functions to own module.

commit 1a26e19338e73f8849c671471dd15cc3c1b1fe82
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 15:51:15 2025 +0200

    Split up models.py.

commit 61f1ccd10f721b0ff4dc1eccf30c7a1ee13f204d
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 12:05:28 2025 +0200

    Move utility function into own modules.

commit 84b341ed35e2c5387819a8b9f9d41eca900ae79f
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 11:44:24 2025 +0200

    Refactor auth functions use.

commit 923e311e3da5b26d85845c2832b73b7b17c48adb
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 11:35:52 2025 +0200

    Refactor route nameing and fix bugs along the way.

commit f0a5c4419c340e62a2615c60b2a9de28204d2995
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 10:34:33 2025 +0200

    Fix URL endpoints in announcement template.

commit b74d74542a1c8dc350749e4788a9464d067a88b5
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 09:25:53 2025 +0200

    Move announcements to own module.

commit 9563a28021ac46c82c04fe4649b394dbf96f92c7
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 09:16:30 2025 +0200

    Combine Company view and edit templates.

commit 6687c373e681d54e4deab6b2582fed5cea9aadf6
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 08:17:42 2025 +0200

    Move Users, Company and System Administration to own modules.

commit 8b7894a2e3eb84bb059f546648b6b9536fea724e
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 07:40:57 2025 +0200

    Move Teams and Projects to own modules.

commit d11bf059d99839ecf1f5d7020b8c8c8a2454c00b
Author: Jens Luedicke <jens@luedicke.me>
Date:   Mon Jul 7 07:09:33 2025 +0200

    Move Tasks and Sprints to own modules.

models/invitation.py

@@ -0,0 +1,56 @@
+"""
+Invitation model for company email invites
+"""
+
+from datetime import datetime, timedelta
+from . import db
+import secrets
+import string
+
+
+class CompanyInvitation(db.Model):
+    """Company invitation model for email-based registration"""
+    id = db.Column(db.Integer, primary_key=True)
+    company_id = db.Column(db.Integer, db.ForeignKey('company.id'), nullable=False)
+    email = db.Column(db.String(120), nullable=False)
+    token = db.Column(db.String(64), unique=True, nullable=False)
+    role = db.Column(db.String(50), default='Team Member')  # Role to assign when accepted
+    
+    # Invitation metadata
+    invited_by_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
+    created_at = db.Column(db.DateTime, default=datetime.now)
+    expires_at = db.Column(db.DateTime, nullable=False)
+    
+    # Status tracking
+    accepted = db.Column(db.Boolean, default=False)
+    accepted_at = db.Column(db.DateTime)
+    accepted_by_user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
+    
+    # Relationships
+    company = db.relationship('Company', backref='invitations')
+    invited_by = db.relationship('User', foreign_keys=[invited_by_id], backref='sent_invitations')
+    accepted_by = db.relationship('User', foreign_keys=[accepted_by_user_id], backref='accepted_invitation')
+    
+    def __init__(self, **kwargs):
+        super(CompanyInvitation, self).__init__(**kwargs)
+        if not self.token:
+            self.token = self.generate_token()
+        if not self.expires_at:
+            self.expires_at = datetime.now() + timedelta(days=7)  # 7 days expiry
+    
+    @staticmethod
+    def generate_token():
+        """Generate a secure random token"""
+        alphabet = string.ascii_letters + string.digits
+        return ''.join(secrets.choice(alphabet) for _ in range(32))
+    
+    def is_expired(self):
+        """Check if invitation has expired"""
+        return datetime.now() > self.expires_at
+    
+    def is_valid(self):
+        """Check if invitation is valid (not accepted and not expired)"""
+        return not self.accepted and not self.is_expired()
+    
+    def __repr__(self):
+        return f'<CompanyInvitation {self.email} to {self.company.name}>'