feat: add iCloud vault support and launcher command installation

- Add new /install-claudesidian-command to create shell alias for launching vault from anywhere
- Add automatic iCloud Drive vault detection in init-bootstrap
- Add iCloud-specific search path with maxdepth 5 for nested structure
- Add fallback prompt asking about iCloud if vault not found
- Update README with launcher command documentation and usage examples
- Shell command auto-resumes existing sessions or starts new ones

This addresses user feedback about iCloud vault detection and adds convenient
shell launcher similar to obsidian-cli pattern.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.claude/commands/install-claudesidian-command.md

@@ -0,0 +1,131 @@
+---
+allowed-tools: [Read, Write, Bash]
+description: Install claudesidian shell command to launch Claude Code from anywhere
+argument-hint: (optional shell: bash/zsh/fish)
+---
+
+# Install Claudesidian Command
+
+Creates a shell alias/function that allows you to run `claudesidian` from anywhere
+to open your vault in Claude Code.
+
+## Task
+
+Install a shell command that:
+1. Changes to your claudesidian vault directory
+2. Launches Claude Code
+3. Works from any directory in your terminal
+
+Similar to having a quick launcher for your vault.
+
+## Process
+
+### 1. **Detect Current Setup**
+
+- Check which shell the user is using (bash/zsh/fish)
+- Find the current working directory (vault path)
+- Determine the appropriate config file
+
+### 2. **Create the Command**
+
+The command will be an alias that:
+- Changes to the vault directory: `cd /path/to/your/vault`
+- Tries to resume existing session: `claude --resume 2>/dev/null`
+- Falls back to new session if no existing one: `|| claude`
+- All in one command: `(cd /path/to/vault && (claude --resume 2>/dev/null || claude))`
+
+This automatically enters resume mode if there's an existing session, or starts a new one if not.
+
+### 3. **Install to Shell Config**
+
+Add the alias to the appropriate config file:
+- **Bash**: `~/.bashrc` or `~/.bash_profile`
+- **Zsh**: `~/.zshrc`
+- **Fish**: `~/.config/fish/config.fish`
+
+### 4. **Verify Installation**
+
+- Show the added line
+- Remind user to reload their shell or source the config
+- Provide test command
+
+## Shell Detection
+
+```bash
+# Detect current shell
+if [ -n "$ZSH_VERSION" ]; then
+  SHELL_TYPE="zsh"
+  CONFIG_FILE="$HOME/.zshrc"
+elif [ -n "$BASH_VERSION" ]; then
+  SHELL_TYPE="bash"
+  # Prefer .bashrc on Linux, .bash_profile on macOS
+  if [ -f "$HOME/.bashrc" ]; then
+    CONFIG_FILE="$HOME/.bashrc"
+  else
+    CONFIG_FILE="$HOME/.bash_profile"
+  fi
+elif [ -n "$FISH_VERSION" ]; then
+  SHELL_TYPE="fish"
+  CONFIG_FILE="$HOME/.config/fish/config.fish"
+fi
+```
+
+## Installation Steps
+
+1. **Get vault path**: Use `pwd` to get current directory
+2. **Check if already installed**: Search config file for existing `claudesidian` alias
+3. **Add alias**: Append to config file if not present
+4. **Show success message**: With instructions to reload shell
+
+## Example Output
+
+```
+🔧 Installing claudesidian command...
+
+📁 Vault path: /home/user/my-vault
+🐚 Shell detected: zsh
+📝 Config file: /home/user/.zshrc
+
+✅ Installed! Added to /home/user/.zshrc:
+   alias claudesidian='(cd /home/user/my-vault && (claude --resume 2>/dev/null || claude))'
+
+🔄 To activate, run:
+   source ~/.zshrc
+
+   Or start a new terminal session.
+
+✨ Test it: Type 'claudesidian' from any directory!
+```
+
+## Important Notes
+
+- The command uses a subshell `()` so it returns to your original directory after
+- Automatically tries to resume existing sessions, falls back to new session
+- If alias already exists, ask user if they want to replace it
+- Always show what will be added before modifying config files
+- Create backup of config file before modifying
+
+## Usage Examples
+
+Install for current shell:
+```
+/install-claudesidian-command
+```
+
+Install for specific shell:
+```
+/install-claudesidian-command zsh
+/install-claudesidian-command bash
+```
+
+## How It Works
+
+The alias uses a clever pattern:
+```bash
+alias claudesidian='(cd /path/to/vault && (claude --resume 2>/dev/null || claude))'
+```
+
+1. `(cd /path/to/vault && ...)` - Subshell that changes directory temporarily
+2. `claude --resume 2>/dev/null` - Tries to resume existing session, suppresses error
+3. `|| claude` - If resume fails (no session), starts new session
+4. After Claude exits, returns to original directory automatically