feat(cli): add skill installer command (ab skill)

Adds new subcommands for managing Claude Code skills:
- ab skill list: Show installed skills (project and user level)
- ab skill info <name>: Show detailed skill metadata
- ab skill install <source>: Install from GitHub or local path
- ab skill remove <name>: Remove installed skills
- ab skill sync: Sync skills to .claude-plugin directory

Supports multiple source formats:
- GitHub shorthand: owner/repo
- Git URLs: https://github.com/...
- Local paths: ./path/to/skill

Closes ab-nmwy

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: thrashr888

Cargo.toml

@@ -61,6 +61,7 @@ thiserror = "2.0"
 
 # File system utilities
 dirs = "5.0"
+tempfile = "3.13"
 
 # Logging
 tracing = "0.1"
@@ -82,4 +83,3 @@ prometheus = "0.14.0"
 lazy_static = "1.5.0"
 
 [dev-dependencies]
-tempfile = "3.13"

src/commands.rs

@@ -95,6 +95,7 @@ Usage:
   human              Send a message to human operator
   swarm              Agent swarm management commands
   agent              Coding agent configuration (Claude Code, Cursor, etc.)
+  skill              Manage skills (list, install, remove, sync)
   handoff            Hand off a bead to an AI agent (fire and forget)
 
 {cyan}Analysis:{reset}
@@ -782,6 +783,10 @@ pub enum Commands {
     #[command(subcommand, name = "agent")]
     CodingAgent(CodingAgentCommands),
 
+    /// Manage skills (install, remove, list)
+    #[command(subcommand)]
+    Skill(SkillCommands),
+
     /// Hand off a bead to an AI agent
     Handoff {
         /// Bead ID to hand off (e.g., ab-xyz)
@@ -2167,3 +2172,78 @@ pub enum CodingAgentCommands {
         path: String,
     },
 }
+
+// =========================================================================
+// SKILL MANAGEMENT
+// =========================================================================
+
+#[derive(Subcommand, Debug)]
+pub enum SkillCommands {
+    /// List available and installed skills
+    List {
+        /// Show all available skills (including from marketplaces)
+        #[arg(short, long)]
+        all: bool,
+
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+
+        /// Path to project (default: current directory)
+        #[arg(default_value = ".")]
+        path: String,
+    },
+
+    /// Show detailed skill information
+    Info {
+        /// Skill name or source (owner/repo, owner/repo/skills/name)
+        name: String,
+    },
+
+    /// Install a skill from various sources
+    Install {
+        /// Skill source: GitHub shorthand (owner/repo), git URL, or local path
+        source: String,
+
+        /// Install globally (user-level) instead of project-level
+        #[arg(short, long)]
+        global: bool,
+
+        /// Target specific agents (claude-code, cursor, codex, etc.)
+        #[arg(short, long)]
+        agent: Option<Vec<String>>,
+
+        /// Specify skill name(s) to install from a multi-skill repo
+        #[arg(short, long)]
+        skill: Option<Vec<String>>,
+
+        /// Skip confirmation prompts
+        #[arg(short, long)]
+        yes: bool,
+    },
+
+    /// Remove an installed skill
+    Remove {
+        /// Skill name to remove
+        name: String,
+
+        /// Remove from global (user-level) instead of project-level
+        #[arg(short, long)]
+        global: bool,
+
+        /// Skip confirmation prompts
+        #[arg(short, long)]
+        yes: bool,
+    },
+
+    /// Sync skills to Claude config directories
+    Sync {
+        /// Specific skill to sync (default: all)
+        #[arg(short, long)]
+        name: Option<String>,
+
+        /// Path to project (default: current directory)
+        #[arg(default_value = ".")]
+        path: String,
+    },
+}