chore(ci): run CI tooling on werf 3 dev

[alexey-igrychev]

Summary

Run website production/preview deployment, content validation and registry cleanup with werf 3 dev instead of werf 2.

What

• Install werf through werf/trdl/actions/setup-app@v0.13.0 with explicit group 3, channel dev.
• Preserve an existing matching trdl repository with force: false; a mismatched repository URL fails instead of being replaced.
• VERIFIED: the official action selects the published 3/dev release and preserves repository state on a second invocation in an isolated macOS smoke test.
• Leave workflow triggers, chart/config files, local development helpers and generated user CI examples unchanged.
• The channel is intentionally moving, including production jobs; the first v3 build can rebuild caches, and v3 cleanup can remove v2-era images under retention policies.
• UNVERIFIED: live deployment/build and cleanup behavior against existing infrastructure; validate in the target environment before merging.

Why

werf/actions/install@v2 hardcodes major 2 and rejects major-3 version inputs. The pinned official trdl action supports an explicit group/channel without a custom installer or changing product version defaults.

[alexey-igrychev]

Verification

• Executed the tagged action's actual dist/index.mjs with isolated HOME, trdl state, tool cache and GitHub environment files: cold and warm runs passed, selected werf v3.6.1, exported TRDL_USE_WERF_GROUP_CHANNEL=3 dev; the warm run did not remove/re-add the repository. Host: macOS arm64, Node 26; a Linux/Node 24 runner was not exercised.
• Scoped actionlint passed with the repositories' custom runner labels declared. Parsed workflow comparison permits only the installer changes and, in werf/werf, removal of the obsolete flag.
• werf 3.6.1 config rendering passed for test and production; offline chart rendering passed for test and the EU production variant. No live resource-schema validation, deployment or cleanup was run.

Follow-up

• Validate production cluster schemas and the first registry cleanup dry-run before merging.