chore: cap every CI job with timeout-minutes (closes #294)

No workflow set timeout-minutes, so a hung build or browser held the
shared runner until the server's own limit, hours later. check now stops
at 10 minutes, e2e-firefox at 15 and e2e-chrome at 20: each is over two
and a half times the job's slowest cold-cache run. README "In CI" records
the measured times and the caps.

Model: opus-5-5

TODO.md

@@ -45,6 +45,12 @@ but the review is broader than any of them.
 
 # Completed Steps
 
+- 2026-10-05: Every CI job has a `timeout-minutes` cap
+  ([#294](https://git.eeqj.de/sneak/AutistMask/issues/294)): `check` 10 minutes,
+  `e2e-firefox` 15 and `e2e-chrome` 20, each over two and a half times the job's
+  slowest cold-cache run. A hung build or browser now ends its job instead of
+  holding the shared runner for hours.
+
 - 2026-10-05: `PROXY_METHODS` in `src/background/index.js` no longer lists
   `eth_chainId` and `net_version`
   ([#326](https://git.eeqj.de/sneak/AutistMask/issues/326)). `handleRpc` answers