docs: add stacktree to projects (#290)

Co-authored-by: Steve Smith <[email protected]>

data/projects/stacktree.yaml

@@ -0,0 +1,46 @@
+name: Stacktree
+repo: https://github.com/stevysmith/stacktree-skill
+tagline: Publish HTML from your agent to a private, unguessable link
+description: >-
+  Turns HTML an agent produced into a link a person can open — a report, a
+  dashboard, a brief. Links are unguessable and uncrawlable by default, with an
+  optional passcode and expiry, and republishing replaces the page in place so a
+  shared URL stays current. Connects as a local MCP server, and the skill is
+  fetchable over HTTP so it stays current without reinstalling. Free anonymous
+  pages need no account at all; agents with a wallet can pay per page over x402
+  instead of signing up.
+scope:
+  - global
+  - project
+tags:
+  - mcp
+  - skills
+  - hosting
+  - publishing
+  - html
+  - sharing
+  - x402
+homepage: https://stacktr.ee/agents
+installation: |
+  Skill over HTTP (always current, no install):
+
+  ```json
+  { "skills": { "urls": ["https://stacktr.ee/.well-known/skills/"] } }
+  ```
+
+  MCP server (adds publish/update tools):
+
+  ```json
+  {
+    "mcp": {
+      "stacktree": {
+        "type": "local",
+        "command": ["npx", "-y", "stacktree-mcp"],
+        "enabled": true,
+        "environment": { "STACKTREE_API_KEY": "{env:STACKTREE_API_KEY}" }
+      }
+    }
+  }
+  ```
+
+  Or run `npx stacktree-install` and pick OpenCode, which writes both.