[Multi-User Part 2]: Add login pages and gate access to application behind login wall

[sabaimran]

Incoming

• Make most routes conditional on authentication if anonymous mode is not enabled. If anonymous mode is enabled, it scaffolds a default user and uses that for all application interactions.
• Add a basic login page and add routes for redirecting the user if logged in

[gitguardian[bot]]

⚠️ GitGuardian has uncovered 2 secrets following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secrets in your pull request

| GitGuardian id | Secret | Commit | Filename | | | -------------- | ------------------------- | ---------------- | --------------- | -------------------- | | [8175313](https://dashboard.gitguardian.com/incidents/8175313?occurrence=115308712) | Django Secret Key | 869c37f4aac0963529fef8650c12feaa6edb9727 | src/app/settings.py | [View secret](https://github.com/khoj-ai/khoj/commit/869c37f4aac0963529fef8650c12feaa6edb9727#diff-131c5c27cd822962a341b4700640cbecac31937b15c46b1df90c569c918f09e3R24) | | [8175313](https://dashboard.gitguardian.com/incidents/8175313?occurrence=116432382) | Django Secret Key | 6fa925e898e431d5ace1cf1780960f655dc433f3 | src/app/settings.py | [View secret](https://github.com/khoj-ai/khoj/commit/6fa925e898e431d5ace1cf1780960f655dc433f3#diff-131c5c27cd822962a341b4700640cbecac31937b15c46b1df90c569c918f09e3L24) |

🛠 Guidelines to remediate hardcoded secrets

1. Understand the implications of revoking this secret by investigating where it is used in your code. 2. Replace and store your secrets safely. [Learn here](https://blog.gitguardian.com/secrets-api-management?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) the best practices. 3. Revoke and [rotate these secrets](https://docs.gitguardian.com/secrets-detection/detectors/specifics/secret_key_in_django_config#revoke-the-secret?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment). 4. If possible, [rewrite git history](https://blog.gitguardian.com/rewriting-git-history-cheatsheet?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment). Rewriting git history is not a trivial act. You might completely break other contributing developers' workflow and you risk accidentally deleting legitimate data. To avoid such incidents in the future consider - following these [best practices](https://blog.gitguardian.com/secrets-api-management/?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) for managing and storing secrets including API keys and other credentials - install [secret detection on pre-commit](https://docs.gitguardian.com/ggshield-docs/integrations/git-hooks/pre-commit?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) to catch secret before it leaves your machine and ease remediation.

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<sup>🦉 GitGuardian detects secrets in your source code to help developers and security teams secure the modern development process. You are seeing this because you or someone else with access to this repository has authorized GitGuardian to scan your pull request.

Our GitHub checks need improvements? Share your feedbacks!</sup>