feat(spawn-session): skill wrapping claude-tmux to spawn Remote-Control sessions

Thin /spawn-session skill that resolves a project name and shells out to the
claude-tmux script to launch a new detached tmux Claude Code session with
Remote Control. Installed into the active profile; README catalogue updated.

Claude-Session: https://claude.ai/code/session_014oa7T7z1h5n34vu8vX9zGT

skills/spawn-session/SKILL.md

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+---
+name: spawn-session
+description: >
+  Spawn a new detached tmux session running Claude Code with Remote Control enabled,
+  in a project's directory, named after the project (e.g. "Agent Runtimes #2"). Use when
+  the user wants to start a separate Claude Code session for another project that they can
+  attach to over VPN/tmux later or drive from the Claude app. Wraps the claude-tmux script.
+allowed-tools: Bash(claude-tmux *), Bash(ls *), Bash(tmux ls), Bash(tmux list-sessions *)
+---
+
+# Spawn Session Skill
+
+Spawn a new, independent Claude Code session inside a detached `tmux` session with
+Remote Control enabled, so the user can attach to it later (`tmux attach`) or control it
+from the Claude app. This wraps the `claude-tmux` script — you do not reimplement its logic.
+
+## Pre-gathered context
+
+### Available projects (folders under ~/dev/claude and ~/dev/claude/projects)
+!`ls -d "$HOME"/dev/claude/*/ "$HOME"/dev/claude/projects/*/ 2>/dev/null`
+
+### Existing tmux sessions
+!`tmux list-sessions -F '#{session_name}' 2>/dev/null || echo "(no tmux server running)"`
+
+## Instructions
+
+1. **Determine the project.** The user's argument is: `$ARGUMENTS`.
+   - If it names a project (a folder basename from the list above, e.g. `agent-runtimes`
+     or `cluster-bootstrap`), use it.
+   - If it is empty, ask the user which project to spawn a session for, offering the list
+     above. Do not guess.
+   - Flags the user may include and you should pass straight through: `--mode <name>`,
+     `--profile <name>`, `--name "<display>"`, `--attach`, `--dryrun`.
+
+2. **Spawn it.** Run:
+   ```
+   claude-tmux <project> [flags]
+   ```
+   The script resolves the folder, picks the engagement mode (the profile's `last-mode`
+   unless `--mode` is given), Title-Cases the project into a session name, auto-increments
+   with a ` #N` suffix if that name is already taken, creates the detached tmux session in
+   the project's directory, and launches Claude Code with `--remote-control` under it.
+
+   Do **not** pass `--attach` unless the user explicitly asked to attach — the point is
+   usually to leave it running detached for later. The default profile is
+   `oreillyit-anthropic`; only override with `--profile` if the user asks.
+
+3. **Report back** exactly what the script prints: the session name, how to attach
+   (`tmux attach -t "<name>"`), and the Remote-Control name to look for in the Claude app.
+   If the user is on a machine without power (the common reason for this), remind them the
+   session persists on the host and is reachable over the VPN via `tmux attach` whenever
+   they reconnect.
+
+## Notes
+
+- This starts a **new, separate** Claude Code process — it is not a sub-agent and does not
+  share this conversation's context. It is a full interactive session the user drives.
+- Remote Control registers in the Claude app only once `claude` is actually running inside
+  the tmux session; `claude-tmux` guarantees this by passing the mode explicitly (never
+  leaving the launcher stalled at an interactive picker).
+- To preview without creating anything, pass `--dryrun`.