Import upstream v0.16.22, stripped

Upstream commit: 474dd0229cb20cf513036619781ed97bd8073c3f
Enterprise-only files removed or emptied: 63
Enterprise-only snippets removed: 117 in 50 files
Dangling module declarations removed: 5
Cargo edits turning enterprise off: 14
Verification: clean
Enterprise feature gates left for rebuilt features: 19 in 18 files

Produced by tools/fork/strip.py. The full report is in docs/fork/strip-reports/ on main.

tests/resources/imap/015.txt

@@ -0,0 +1,22 @@
+From: "=?koi8-r?B?4czFy9PBzsTS?=" <[email protected]>
+To: [email protected]
+Date: Sat, 02 Aug 2026 10:15:05 +0300
+Subject: =?koi8-r?B?+sHQ0s/T?=
+MIME-Version: 1.0
+Content-Type: multipart/mixed; boundary="BOUND1"
+
+--BOUND1
+Content-Type: text/plain; charset=koi8-r
+Content-Transfer-Encoding: quoted-printable
+
+test body
+--BOUND1
+Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document;
+	name="=?koi8-r?B?+sHQ0s/TIObp8yD0+i5kb2N4?="
+Content-Disposition: attachment;
+	filename="=?koi8-r?B?+sHQ0s/TIObp8yD0+i5kb2N4?="; size=10
+Content-Description: =?koi8-r?B?0NLJzM/Wxc7JxQ==?=
+Content-Transfer-Encoding: base64
+
+dGVzdA==
+--BOUND1--