[Feat] DB (MySQL) 추가 및 models, repositories, services layer 개발

[Zerohertz]

What type of PR is this?

• feat
• fix
• refactor
• test
• infra
• ci/cd
• docs
• chore

What this PR does / why we need it

• DB (MySQL) manifest 추가 및 연결
• models, repositories, services layer 개발
  • SQLAlchemy 사용
• Dependency injection 사용

Which issue(s) this PR fixes

Fixes #8

Special notes for your reviewer

Does this PR introduce a user-facing change?

- DB (MySQL) manifest 추가 및 연결
- `models`, `repositories`, `services` layer 개발
    - `SQLAlchemy` 사용
- Dependency injection 사용

Additional documentation

[codecov]

Codecov Report

Attention: Patch coverage is 81.63265% with 54 lines in your changes missing coverage. Please review.

Project coverage is 83.20%. Comparing base (375772e) to head (e42b7e5).
Report is 18 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
app/repositories/base.py	58.00%	18 Missing and 3 partials ⚠️
app/services/base.py	68.57%	9 Missing and 2 partials ⚠️
app/exceptions/users.py	0.00%	5 Missing ⚠️
app/schemas/responses.py	28.57%	5 Missing ⚠️
app/core/configs.py	82.60%	2 Missing and 2 partials ⚠️
app/core/database.py	85.71%	3 Missing ⚠️
app/api/v1/endpoints/users.py	92.30%	2 Missing ⚠️
app/services/users.py	88.23%	0 Missing and 2 partials ⚠️
app/core/lifespan.py	85.71%	0 Missing and 1 partial ⚠️

@@            Coverage Diff             @@
##             main      #16      +/-   ##
==========================================
- Coverage   90.71%   83.20%   -7.51%     
==========================================
  Files          20       29       +9     
  Lines         280      518     +238     
  Branches       20       31      +11     
==========================================
+ Hits          254      431     +177     
- Misses         17       68      +51     
- Partials        9       19      +10     

Components	Coverage Δ
api/v1	95.23% <92.30%> (-4.77%)	⬇️
core	88.80% <87.30%> (-1.83%)	⬇️
exceptions	45.94% <58.33%> (-44.68%)	⬇️
models	100.00% <100.00%> (∅)
repositories	63.79% <63.79%> (∅)
schemas	82.97% <73.68%> (-2.03%)	⬇️
services	76.78% <75.00%> (-23.22%)	⬇️
utils	85.93% <ø> (ø)

Files with missing lines	Coverage Δ
app/core/container.py	100.00% <100.00%> (ø)
app/core/router.py	100.00% <100.00%> (ø)
app/exceptions/base.py	100.00% <100.00%> (ø)
app/exceptions/database.py	100.00% <100.00%> (ø)
app/exceptions/handlers.py	57.14% <100.00%> (-21.43%)	⬇️
app/main.py	100.00% <100.00%> (ø)
app/models/base.py	100.00% <100.00%> (ø)
app/models/users.py	100.00% <100.00%> (ø)
app/repositories/users.py	100.00% <100.00%> (ø)
app/schemas/base.py	100.00% <100.00%> (ø)
... and 13 more

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2e9e87e...e42b7e5. Read the comment docs.