feat: add --no-workspace-macros opt-out for workspace macro loading

Mirrors --no-workspace-mcp exactly: a CLI-only flag backed by an
AppConfig field (default false) that disables .coyote/macros in both
the resolved macro policy and Macro::load's workspace-then-global
preference, so the two always agree (custom-commands design §5).

src/cli/mod.rs

@@ -96,6 +96,9 @@ pub struct Cli {
     /// Disable loading workspace MCP servers from .coyote/mcp.json, .coyote/.mcp.json, or .mcp.json
     #[arg(long)]
     pub no_workspace_mcp: bool,
+    /// Disable loading workspace macros from .coyote/macros
+    #[arg(long)]
+    pub no_workspace_macros: bool,
     /// Disable memory for this invocation
     #[arg(long)]
     pub no_memory: bool,