refactor(#1763): ADR-1235 agent migration — cut over the trivial-converter group to the descriptor path (#1764)

ADR-1235 step 1: route the trivial-converter runtime group (cursor, windsurf, augment, trae, codebuddy) off the inline install() agent loop onto the descriptor-driven installRuntimeArtifacts path. Establishes the converter-context foundation (pre-converter cross-cutting + no agent-stamp). Agent install output is byte-identical for all 16 runtimes (golden-parity, global + verified local). cline deliberately excluded (local rules-only). Closes #1763.

capabilities/cursor/capability.json

@@ -36,6 +36,14 @@
           "nesting": "flat",
           "recursive": false,
           "converter": "convertClaudeCommandToCursorCommand"
+        },
+        {
+          "kind": "agents",
+          "destSubpath": "agents",
+          "prefix": "gsd-",
+          "nesting": "flat",
+          "recursive": false,
+          "converter": "convertClaudeAgentToCursorAgent"
         }
       ],
       "local": [
@@ -54,6 +62,14 @@
           "nesting": "flat",
           "recursive": false,
           "converter": "convertClaudeCommandToCursorCommand"
+        },
+        {
+          "kind": "agents",
+          "destSubpath": "agents",
+          "prefix": "gsd-",
+          "nesting": "flat",
+          "recursive": false,
+          "converter": "convertClaudeAgentToCursorAgent"
         }
       ]
     },