Fix development cache key auth context

[3em0]

Summary

• add a separate SHA-256 development-cache fingerprint with a schema version
• include request headers/kwargs plus session cache context such as default headers and cookies in the cache key
• keep scheduler deduplication fingerprints unchanged while preventing auth/cookie cache reuse
• update development-cache docs and add regression tests

Fixes #311

Tests

• /tmp/scrapling-agent-verify-venv/bin/python -m pytest tests/spiders -q
• /tmp/scrapling-agent-verify-venv/bin/python -m ruff check scrapling/spiders/request.py scrapling/spiders/session.py scrapling/spiders/engine.py tests/spiders/test_cache.py tests/spiders/test_session.py