Supersede all old keys with 75681C8167312680

Executed the full supersession ceremony:

- ceremonies/: signed record of the supersession
  (signed by both old keys plus the new one)
- history/: added final states of
  344EA5AB10D868E0 (main key from 2020 to 2026) and
  6D11C1E91D3B0265 (main key for 5 months in 2026),
  both revoked as "superseded" and cross-certifying the new key
- snapshots/: first export of 75681C8167312680 as published,
  certified by both predecessors, verified on keys.openpgp.org
- the UID alexander@hess.software is revoked and withdrawn

All five keyservers, WKD (three domains), and the `git` forges
serve only the new key from now on.

ceremonies/2026-07-08_supersession.md

@@ -0,0 +1,36 @@
+# Key Supersession
+
+Effective immediately (i.e., as of 2026-07-08),
+    my only valid OpenPGP key is:
+
+````
+ed25519, created 2026-07-08
+8B11 40AD B518 5334 E9FA  513B 7568 1C81 6731 2680
+Alexander Hess <ah@alexander-hess.com>
+Alexander Hess <alexander@webartifex.biz>
+Alexander Hess <alexander@webartifex.de>
+````
+
+The following keys are revoked as superseded:
+
+````
+rsa4096, created 2020-07-17   (main key from 2020 to 2026)
+AB5C 0E31 9D77 350F BA6C  F143 344E A5AB 10D8 68E0
+
+ed25519, created 2026-02-16   (main key for 5 months in 2026)
+E882 EE15 1EB9 0703 133D  FE9F 6D11 C1E9 1D3B 0265
+````
+
+Further, the address `alexander@hess.software`
+    is withdrawn for now and will not be used in the new key.
+
+Both old keys have certified the new key.
+
+Fetch and verify yourself:
+
+````bash
+gpg --keyserver hkps://keys.openpgp.org --recv-keys 8B1140ADB5185334E9FA513B75681C8167312680
+gpg --check-signatures 8B1140ADB5185334E9FA513B75681C8167312680
+````
+
+This file is signed with both the old keys and the new one.