Bump the golangci-lint Docker image pin in Dockerfile and the
release-archive sha256 pins in script/bootstrap from 2.11.3 to
2.12.2, and replace .golangci.yml with the canonical config. The
canonical config moves lll/funlen/cyclop/dupl settings from the
top-level linters-settings key (ignored by the v2 schema) to
linters.settings, so those thresholds now actually apply.
Fix all findings the newly applied thresholds surfaced:
- lll: wrap or shorten seven over-length lines (struct tag
comments, test logger construction, a func signature, and a
nosec comment)
- goconst: use http.MethodPost/http.MethodPut and new shared
constants for repeated test strings; add tmplKeyError and
tmplKeyWebhook constants for template data keys in handlers
- dupl: merge buildHTTPTargetConfig and buildSlackTargetConfig
into a parameterized buildURLTargetConfig; drop the duplicate
iWebhookDB test helper in favor of testWebhookDB; extract
shared helpers in middleware and session tests
