Distribution repo skeleton

One `npx skills add ssh://gitea/agent-skills/skills` now offers all five
skills in a grouped multi-select list. Groups come from
.claude-plugin/marketplace.json: writing-clarity, windows-tools,
image-to-data.

skills/ holds real copies rather than submodules or pointers. The installer
clones without --recurse-submodules (git.ts:241), so a submodule directory
would arrive empty, and it skips remote sources declared in a marketplace
manifest (plugin-manifest.ts:89), so only in-repo paths are resolvable.

Grouping applies only to skills listed explicitly under a plugin's skills
array with a ./-prefixed path (plugin-manifest.ts:147-151); anything not
listed falls into "Other".

think-twice and teach-me share a group because teach-me's SKILL.md points at
double-check.md, self-contain.md and style.md inside the think-twice
directory. Installing teach-me alone leaves those pointers unresolved.

Syncing from the five upstream repos is manual for now.

.claude-plugin/marketplace.json

@@ -0,0 +1,31 @@
+{
+  "name": "agent-skills",
+  "owner": {
+    "name": "im0o"
+  },
+  "plugins": [
+    {
+      "name": "writing-clarity",
+      "description": "Rebuild an output so it stands alone and every claim is verified, and teach a subject layer by layer until the reader says they understand.",
+      "skills": [
+        "./skills/think-twice",
+        "./skills/teach-me"
+      ]
+    },
+    {
+      "name": "windows-tools",
+      "description": "Read-only Windows diagnostics: what is filling a drive, and where a file lives.",
+      "skills": [
+        "./skills/disk-master",
+        "./skills/everything-file-search"
+      ]
+    },
+    {
+      "name": "image-to-data",
+      "description": "Turn a picture of a table into structured data.",
+      "skills": [
+        "./skills/baimiao-table-ocr"
+      ]
+    }
+  ]
+}