feat(17-01): richeditor field type on the seaglass sanitizer

- seaglass (new module): bluemonday v1.0.27 policy ported from Journal
  without the Blog Editor rules, byte-stable token comparison,
  SanitizeReport, Sanitize, Check, Removals
- cabana: type richeditor (common keys plus size); every create and update
  value sanitized before Fill, non-string values are a 422, removals become
  meta.notices; settings and relation forms refuse the type
- backend lang richeditor.removed_* and markup_changed (en, pl plurals)
- TestSeaglassSmoke, TestCompanionsRichEditorSmoke, README and docs

go.sum

@@ -74,6 +74,8 @@ github.com/aws/aws-sdk-go-v2/service/sts v1.42.3 h1:ErklX/7uhSbkAAeyQD/Y1OoQ9hO3
 github.com/aws/aws-sdk-go-v2/service/sts v1.42.3/go.mod h1:ULe4HCzfKPiR6R3HEurE3b1upEkuk8AkMrOKtaOxKO8=
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 github.com/aws/smithy-go v1.26.0/go.mod h1:YE2RhdIuDbA5E5bTdciG9KrW3+TiEONeUWCqxX9i1Fc=
+github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
+github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
 github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
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 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
@@ -157,6 +159,8 @@ github.com/googleapis/enterprise-certificate-proxy v0.3.14 h1:yh8ncqsbUY4shRD5dA
 github.com/googleapis/enterprise-certificate-proxy v0.3.14/go.mod h1:vqVt9yG9480NtzREnTlmGSBmFrA+bzb0yl0TxoBQXOg=
 github.com/googleapis/gax-go/v2 v2.19.0 h1:fYQaUOiGwll0cGj7jmHT/0nPlcrZDFPrZRhTsoCr8hE=
 github.com/googleapis/gax-go/v2 v2.19.0/go.mod h1:w2ROXVdfGEVFXzmlciUU4EdjHgWvB5h2n6x/8XSTTJA=
+github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
+github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
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 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
@@ -201,6 +205,8 @@ github.com/mattn/go-sqlite3 v1.14.22 h1:2gZY6PC6kBnID23Tichd1K+Z0oS6nE/XwU+Vz/5o
 github.com/mattn/go-sqlite3 v1.14.22/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
 github.com/mdelapenya/tlscert v0.2.0 h1:7H81W6Z/4weDvZBNOfQte5GpIMo0lGYEeWbkGp5LJHI=
 github.com/mdelapenya/tlscert v0.2.0/go.mod h1:O4njj3ELLnJjGdkN7M/vIVCpZ+Cf0L6muqOG4tLSl8o=
+github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwXFM08ygZfk=
+github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
 github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa15WveJJGw=
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