Add comprehensive authentication guide explaining that Catalogi
supports any OIDC-compliant provider via automatic discovery.

- New authentication.md with generic OIDC setup guide
- Environment variables (OIDC_ISSUER_URI, OIDC_CLIENT_ID, etc.)
- Keycloak configuration example
- Redirect URIs, scopes, troubleshooting, security
- Update sidebar and README with authentication section

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Co-Authored-By: Claude <[email protected]>

- Add automatic session refresh when access token expires
- Store refresh token in database and use it to obtain new access tokens
- Extend cookie lifetime to 7 days (was matching session expiry)
- Remove frontend session polling (now handled by backend)
- Use OIDC provider's expires_in directly (no minimum enforcement)
- Add graceful fallback to logout if refresh fails

This allows users to stay authenticated seamlessly without re-login
as long as the refresh token is valid.

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

Co-Authored-By: Claude <[email protected]>

This reverts commit dd32569.

…ogatives

- Create software_attribute_definitions table with attribute metadata
- Add customAttributes JSONB column to softwares table with GIN index
- Migrate existing prerogatives (isPresentInSupportContract,
  isFromFrenchPublicService, doRespectRgaa) to custom attributes
- Create AttributeKind type ('boolean' | 'string' | 'number' | 'date' | 'url')
- Add AttributeDefinition and AttributeValue types
- Implement repository layer for attribute definitions
- Create getAttributeDefinitions use case
- Remove deprecated Prerogatives type

This enables project-specific attributes without code changes, making
the system more generic and reusable across different deployments.

Note: Type errors remain in use cases, tests, and adapters - will be
fixed in follow-up commits.

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Co-Authored-By: Claude <[email protected]>

feat: add software customAttributes and a table to define them software_attribute_definitions