feat: Add key-related APIs in security-proxy-auth

[lindseysimple]

Resolves #5038. Add key-related APIs in security-proxy-auth to enable support for external JWT verification.

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• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.2% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 15.50802% with 158 lines in your changes missing coverage. Please review.

Project coverage is 27.96%. Comparing base (0ef5369) to head (b41f93f).

Files with missing lines	Patch %	Lines
internal/security/proxyauth/application/key.go	0.00%	41 Missing ⚠️
internal/security/proxyauth/controller/key.go	0.00%	41 Missing ⚠️
internal/pkg/infrastructure/postgres/keystore.go	0.00%	31 Missing ⚠️
internal/pkg/utils/aes.go	67.44%	7 Missing and 7 partials ⚠️
internal/security/proxyauth/router.go	0.00%	7 Missing ⚠️
...ternal/security/proxyauth/controller/controller.go	0.00%	6 Missing ⚠️
internal/security/proxyauth/config/config.go	0.00%	4 Missing ⚠️
internal/security/proxyauth/utils/key.go	0.00%	4 Missing ⚠️
internal/security/proxyauth/container/database.go	0.00%	2 Missing ⚠️
internal/core/command/router.go	0.00%	1 Missing ⚠️
... and 7 more

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5039      +/-   ##
==========================================
- Coverage   28.05%   27.96%   -0.10%     
==========================================
  Files         243      251       +8     
  Lines       17602    17764     +162     
==========================================
+ Hits         4938     4967      +29     
- Misses      11536    11662     +126     
- Partials     1128     1135       +7     

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