Mark stale projects with 🧊, remove archived entries, add Arcane (#1267)

- Add 🧊 marker for 113 stale projects (2+ years inactive)
- Remove 4 archived repos (Centurion, notary, Minio, docker-ls)
- Remove 1 broken link (docker-lock / safe-waters)
- Add Arcane to the Web section
- Replace 💲 with 💴 across README and tooling
- Add 🧊 (MarkerStale) support to Go parser/linter
- Update CONTRIBUTING.md, PR template, issue template, and AGENTS.md

Closes #1260, relates to #1188, #1255

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

internal/parser/parser.go

@@ -23,8 +23,9 @@ var markerDefs = []struct {
 	marker Marker
 }{
 	{text: ":skull:", marker: MarkerAbandoned},
-	{text: ":heavy_dollar_sign:", marker: MarkerPaid},
+	{text: ":yen:", marker: MarkerPaid},
 	{text: ":construction:", marker: MarkerWIP},
+	{text: ":ice_cube:", marker: MarkerStale},
 }
 
 // ParseEntry parses a single markdown list line into an Entry.