feat: let a profile state that its upstream is gone

Saying those profiles would stay open no matter what was wrong. A dead
forge is a verifiable fact, and a fact can be recorded: upstream_gone
carries why, and the profile stops being an open problem. The refs
describe the last revision anyone could reach, which is all any reader
can ask of them.

The declaration is guarded rather than trusted, because a forge can come
back and a profile that keeps asserting a death nobody rechecks is worse
than one that fails loudly. Declared and unreachable reports as a
recorded fact; declared and answering reports as the contradiction it
is, and the profile has to be read again.

yuzu and suyu carry GitHub's 451. citron carries the loss of
git.citron-emu.org and the squatter now sitting on the .com. Each names
what was probed and when, so the next reader retraces it rather than
repeating it.

emulators/citron.yml

@@ -4,6 +4,7 @@ core_classification: community_fork
 source: "https://git.citron-emu.org/citron-emu/Citron"
 upstream: "https://git.citron-emu.org/citron-emu/Citron"
 profiled_date: "2026-03-26"
+upstream_gone: "git.citron-emu.org no longer resolves, and git.citron-emu.com redirects to an unrelated survey site, the domain having been taken. Observed 2026-09-04; no mirror found."
 core_version: "2026.03.12"
 display_name: "Citron (Nintendo Switch)"
 cores:

emulators/suyu.yml

@@ -4,6 +4,7 @@ core_classification: community_fork
 source: "https://github.com/suyu-emu/suyu"
 upstream: "https://github.com/suyu-emu/suyu"
 profiled_date: "2026-03-26"
+upstream_gone: "GitHub withdrew the repository for legal reasons: the API answers HTTP 451. git.suyu.dev still serves a Forgejo page, but its API answers 403 and its raw paths 404, so it carries no readable tree. Observed 2026-09-04."
 core_version: "Yuzu EA 4176 based"
 display_name: "Suyu (Nintendo Switch)"
 cores:

emulators/yuzu.yml

@@ -4,6 +4,7 @@ core_classification: official_port
 source: "https://github.com/yuzu-emu-mirror/yuzu"
 upstream: "https://github.com/yuzu-emu/yuzu"
 profiled_date: "2026-03-26"
+upstream_gone: "GitHub withdrew the repository for legal reasons: the API answers HTTP 451 for both yuzu-emu/yuzu and the yuzu-emu-mirror copy. Observed 2026-09-04; no mirror found that serves file content."
 core_version: "EA 4176"
 display_name: "Yuzu (Nintendo Switch)"
 cores: