feat(auth): install all authentication providers by default

All authentication methods (Basic Auth, Flask-Login, OAuth) are now
installed as core dependencies instead of optional extras. This
simplifies setup and eliminates the need to run `uv sync --extra auth-*`
when switching between authentication methods.

Changes:
- Move authlib, bcrypt, and flask-login to core dependencies
- Remove auth-* optional dependency groups from pyproject.toml
- Update documentation to remove installation instructions
- Simplify troubleshooting and migration guides

Benefits:
- No import errors when switching auth methods
- Simpler user experience
- All providers available out of the box

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,10 @@ version = "1.8.0"
 description = "Backup server side executed python scripts for managing linux and windows system and application data backups, developed by adminsys for adminsys"
 readme = "README.md"
 dependencies = [
+    "authlib>=1.3.0",
+    "bcrypt>=4.0.0",
     "flask==3.1.0",
+    "flask-login>=0.6.0",
     "huey==2.5.3",
     "iniparse==0.5",
     "paramiko==3.5.1",
@@ -19,12 +22,6 @@ dependencies = [
 requires-python = ">=3.13"
 
 [project.optional-dependencies]
-# Authentication providers
-auth-basic = ["bcrypt>=4.0.0"]
-auth-login = ["flask-login>=0.6.0", "bcrypt>=4.0.0"]
-auth-oauth = ["authlib>=1.3.0", "requests>=2.32.0"]
-# Install all auth providers
-auth-all = ["bcrypt>=4.0.0", "flask-login>=0.6.0", "authlib>=1.3.0", "requests>=2.32.0"]
 # Documentation dependencies
 docs = [
     "docutils",