feat: implement stale-while-revalidate for HTTP cache #17415

Job	Run time
Check if node constants are up to date	5s
cargo deny	33s
Build C library (ubuntu-latest)	8m 7s
Rust doc comments	24s
Build C library (macos-latest)	2m 41s
Lint Rust	2m 45s
Check provider database	6s
Rust tests (ubuntu-latest, 1.83.0)	3m 20s
Rust tests (windows-latest, 1.83.0)	9m 29s
Python lint	12s
Rust tests (macos-latest, 1.83.0)	4m 33s
Rust tests (ubuntu-latest, 1.81.0)	3m 40s
Build deltachat-rpc-server (ubuntu-latest)	3m 10s
Build deltachat-rpc-server (macos-latest)	3m 7s
Build deltachat-rpc-server (windows-latest)	6m 28s
JSON-RPC Python tests (ubuntu-latest, 3.13)	1m 46s
JSON-RPC Python tests (macos-latest, 3.13)	2m 20s
JSON-RPC Python tests (windows-latest, 3.13)	3m 7s
JSON-RPC Python tests (ubuntu-latest, pypy3.10)	2m 48s
JSON-RPC Python tests (macos-latest, pypy3.10)	2m 54s
JSON-RPC Python tests (ubuntu-latest, 3.7)	2m 27s
CFFI Python tests (ubuntu-latest, 3.13)	5m 6s
CFFI Python tests (macos-latest, 3.13)	4m 47s
CFFI Python tests (ubuntu-latest, pypy3.10)	5m 50s
CFFI Python tests (macos-latest, pypy3.10)	5m 44s
CFFI Python tests (ubuntu-latest, 3.7)	4m 57s
	1h 30m 26s

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