Saml fix (#5651)

# Description of Changes
When password login is disabled UI changes to have central style SSO
button

<img width="2057" height="1369" alt="image"
src="https://github.com/user-attachments/assets/8f65f778-0809-4c54-a9c4-acf3a67cfa63"
/>

Auto SSO login functionality

Massively increases auth debugging visibility: verbose console logging
in ErrorBoundary, AuthProvider, Landing, AuthCallback.

Improves OAuth/SAML testability: adds Keycloak docker-compose setups +
realm JSON exports + start/validate scripts for OAuth and SAML
environments.

Hardens license upload path handling: better logs + safer directory
traversal protection by normalizing absolute paths before startsWith
check.

UI polish for SSO-only login: new “single provider” centered layout +
updated button styles (pill buttons, variants, icon wrapper, arrow).


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- Why the change was made
- Any challenges encountered

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---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

testing/compose/validate-saml-test.sh

@@ -0,0 +1,58 @@
+#!/bin/bash
+set -e
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m'
+
+echo -e "${YELLOW}Validating SAML test environment...${NC}"
+echo ""
+
+# Check Keycloak health
+echo -n "Checking Keycloak health... "
+if curl -sf http://localhost:9080/health/ready > /dev/null 2>&1; then
+    echo -e "${GREEN}✓${NC}"
+else
+    echo -e "${RED}✗ Keycloak is not ready${NC}"
+    exit 1
+fi
+
+# Check SAML realm
+echo -n "Checking SAML realm... "
+if curl -sf http://localhost:9080/realms/stirling-saml > /dev/null 2>&1; then
+    echo -e "${GREEN}✓${NC}"
+else
+    echo -e "${RED}✗ SAML realm not found${NC}"
+    exit 1
+fi
+
+# Check SAML metadata
+echo -n "Checking SAML metadata endpoint... "
+if curl -sf http://localhost:9080/realms/stirling-saml/protocol/saml/descriptor > /dev/null 2>&1; then
+    echo -e "${GREEN}✓${NC}"
+else
+    echo -e "${RED}✗ SAML metadata not available${NC}"
+    exit 1
+fi
+
+# Check Stirling PDF
+echo -n "Checking Stirling PDF status... "
+if curl -sf http://localhost:8080/api/v1/info/status 2>/dev/null | grep -q "UP"; then
+    echo -e "${GREEN}✓${NC}"
+else
+    echo -e "${RED}✗ Stirling PDF is not ready${NC}"
+    exit 1
+fi
+
+# Check Stirling PDF SAML metadata
+echo -n "Checking Stirling PDF SAML metadata... "
+if curl -sf http://localhost:8080/saml2/service-provider-metadata/keycloak > /dev/null 2>&1; then
+    echo -e "${GREEN}✓${NC}"
+else
+    echo -e "${RED}✗ Stirling PDF SAML metadata not available${NC}"
+    exit 1
+fi
+
+echo ""
+echo -e "${GREEN}All SAML environment checks passed!${NC}"