feat: save keys in mongodb

[Stanford997]

Context

Changes

Screenshot (if applicated)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
app.py	144	78	46%	49–50, 57–64, 69–99, 106, 110, 115, 119, 130, 135, 137, 142, 146, 155–177, 182–228, 233–251, 255
modules
evaluator.py	56	14	75%	96–97, 104–122
job_recommendation_system.py	32	19	41%	23–61
langgraph_qa.py	16	15	6%	2–31
neo4j_model.py	40	28	30%	36–78, 93–104, 110–111, 117–127, 136
parser.py	12	1	92%	20
recommendation_generator.py	25	21	16%	5, 8–38, 51
resume_processor.py	9	5	44%	21–25
retrieval_engine.py	34	25	26%	19–54, 68–103
upload.py	25	3	88%	23, 46–47
verify.py	15	15	0%	1–21
view.py	23	19	17%	5, 11–24, 30–35
TOTAL	431	243	44%

Tests	Skipped	Failures	Errors	Time
11	0 💤	0 ❌	0 🔥	34.906s ⏱️

[Linchen-Xu]

LGTM