docs: feature architecture documentation (batch 6/6 — files 51-62, FINAL)

[ChitkulLakshya]

Summary

Final batch (6/6): Middleware, DB schema, frontend routing/state, API client, env vars, error handling, cross-references, deployment, security, performance, testing (files 51-62).

This completes all 62 feature architecture documentation files.

Files Added (12 files)

#	File	Author
51	middleware-stack-overview.md	eesha264
52	database-schema-models.md	eesha264
53	frontend-routing-layout.md	eesha264
54	frontend-state-management.md	eesha264
55	api-client-interceptors.md	eesha264
56	environment-variables-reference.md	eesha264
57	error-handling-strategy.md	eesha264
58	cross-reference-matrix.md	eesha264
59	deployment-infrastructure.md	eesha264
60	security-architecture.md	eesha264
61	performance-optimization.md	eesha264
62	testing-quality-assurance.md	eesha264

Coverage

• Infrastructure (51-52): Express middleware chain, Mongoose model inventory with indexes
• Frontend (53-55): React Router, TanStack Query + Zustand, Axios interceptors
• Reference (56-58): Complete env var catalog, error handling patterns, cross-reference matrix
• Operations (59-62): Render deployment, security layers, performance optimization, testing strategy

Total Documentation Summary

Batch	Files	PR	Lines
1	00-10	#267	~3,000
2	11-20	#268	2,388
3	21-30	#269	2,179
4	31-40	#270	1,727
5	41-50	#271	1,312
6	51-62	This PR	2,043
Total	62 files	6 PRs	~12,649 lines

Authors

• Thanmayee Reddy Kotha (thanmayeereddykotha): Files 00-30 (30 commits)
• Eeshitha Gone (eesha264): Files 31-62 (32 commits)

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Project	Deployment	Actions	Updated (UTC)
zync	Ready	Preview	Aug 16, 2026 10:36am

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