ci: cache playwright browsers across runs; drop no-op save step

CHANGELOG.md

@@ -14,6 +14,7 @@
 - **CI e2e deploy command stays alive** (`E2E_DEPLOY_CMD` now ends with `docker compose … logs -f`): Playwright's webServer requires a long-running process — `up -d` returns immediately and triggered "Process from config.webServer exited early" (run #16); `logs -f` also streams app logs into CI output for debugging
 - **CI e2e step bypasses proxies for the in-network app host** (`NO_PROXY`/`no_proxy=app,localhost,127.0.0.1,.kkhost.pl`) and prints proxy/DNS/curl diagnostics before the suite — run #18 showed Chromium getting `ERR_SSL_PROTOCOL_ERROR` on http://app:3000 while node-side HTTP worked (9 API-only tests passed), pointing at a TLS-terminating proxy env var that Chromium honors but Node's HTTP client ignores
 - **CI e2e targets the app at a static in-network IP** (`172.39.0.10`, pinned subnet `172.39.0.0/24` created by "Prepare e2e network"; stale networks with other subnets are recreated) instead of the DNS alias — Chromium got `ERR_SSL_PROTOCOL_ERROR` via the hostname while node-side HTTP worked, so DNS is removed from the equation; post-deploy connectivity diagnostics added as a CI-gated globalSetup (`e2e/ci-diagnostics.ts`, no-op locally) comparing node resolution/HTTP against Chromium navigation on both hostname and static IP
+- **CI caches Playwright browser binaries across runs** (`$HOME/.cache/ms-playwright` via actions/cache): the flaky runner uplink makes the ~187 MiB Chrome-for-Testing download unreliable (runs #20/#21 died mid-download at "Install browsers"); also removed the no-op "Save deps cache" step — on this runner caches marked by a restore step are uploaded automatically at job end, so an explicit save never did anything
 - Verified: unit suite 234 green locally; e2e not run locally by design (would deploy to production) — first real pass happens in the PR's CI run
 
 ## v0.12.2 — 2026-09-18 14:06