Add comprehensive unit and e2e test suite (193 tests)

[dianaKhortiuk-frontegg]

Summary

• Adds 193 tests (162 unit + 31 e2e) covering the entire SDK surface — from FronteggConfig through token resolvers, cache services, and Flask/FastAPI secure access middleware
• Test infrastructure uses a session-scoped RSA keypair with real RS256 signature verification (no PyJWT mocking), vendor session fakes, and singleton resetters for test isolation
• Mirrors test patterns from the Node.js SDK (nodejs-sdk): access token resolver routing, cache hit/miss with {empty: True} negative caching sentinel, token-type mismatch detection, and "Api tokens are disabled" 403 handling
• Live e2e tests hit the real Frontegg API (vendor auth, public key fetch, forged JWT rejection) and auto-skip when credentials are absent

Unit tests (22 files, 162 tests)

Area	Files	Tests
Config, context, exceptions, URLs, retry, package utils	6	23
Cache managers (local + Redis via fakeredis)	2	9
Authenticator (sync + async)	2	10
Identity mixin (sync + async)	2	21
Token resolvers (JWT + access token)	2	25
Access token services + cache services	2	22
Token type mismatch detection	1	8
HTTP client, audits client	2	8
Flask adapter (get_auth_header, wrapper)	2	7
FastAPI adapter (User model, wrapper)	2	12

E2E tests (3 files, 31 tests)

Area	Tests
Flask secure access (mocked, real RSA JWTs)	8
FastAPI secure access (mocked, real RSA JWTs)	8
Live Frontegg API (vendor auth, public key, forged JWT rejection, Flask/FastAPI with live vendor token, HttpClient sync+async)	31

How to run

# Unit + mocked e2e (no credentials needed)
PYTHONPATH=. pytest tests/unit tests/e2e -v

# With live Frontegg API tests
FRONTEGG_TEST_CLIENT_ID=... FRONTEGG_TEST_API_KEY=... \
    PYTHONPATH=. pytest tests/unit tests/e2e -v

Test plan

• All 193 tests pass locally (Python 3.9.6)
• Live e2e tests verified against real Frontegg API
• No production code changes — tests only
• CI pipeline validation (may need test deps added to pyproject.toml)

🤖 Generated with Claude Code

[dianaKhortiuk-frontegg]

Superseded by #150 — the full 193-test suite from this PR has been folded into the consolidated 4.0.0 PR, adapted to the new dependency stack (pytest 9 / Python 3.10+ / Flask 3 / FastAPI+starlette 1.x) and verified green (162 passed, 31 skipped). Thanks for the comprehensive coverage!