Add s2-storage skill with reusable upload script

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

s2-storage/SKILL.md

@@ -0,0 +1,35 @@
+---
+name: s2-storage
+description: Upload and manage files on S2, a self-hosted file storage service at s2.connorrhodes.com. Use when the user says "upload to s2", "store this file", "put this on s2", or when any other skill needs to upload a file and get a persistent URL back.
+version: 1.0.0
+---
+
+# S2 Storage
+
+Upload files to `s2.connorrhodes.com` via the API and get back a persistent URL.
+
+## Endpoint
+
+- **URL:** `POST https://api.connorrhodes.com/agent/s2_upload`
+- **Auth:** `x-api-key: LT6CXiLT5cEApfqtThz17bENr6OLP804FepOMqa1tZkfTGXiiCcSFlupl6gaYeX`
+- **Response:** JSON string — the public URL of the uploaded file
+
+## Script
+
+Use `scripts/s2_upload.py` for all uploads. Do not rewrite the curl command inline.
+
+```bash
+# Upload and print the URL
+uv run ~/notes/skills/s2-storage/scripts/s2_upload.py /path/to/file.pdf
+
+# Upload and delete the local file afterwards
+uv run ~/notes/skills/s2-storage/scripts/s2_upload.py /path/to/file.pdf --delete
+```
+
+The script prints the S2 URL to stdout on success and exits non-zero on failure.
+
+## Rules
+
+- Always delete the local file after upload unless the user explicitly wants to keep it. Pass `--delete` to the script.
+- The returned URL is permanent and publicly accessible — treat it as the canonical reference going forward.
+- When another skill needs to upload a file (e.g., log-work-expense, brag-sheet), use this script rather than reimplementing the curl call.