fix(cortex-cli): add model alias resolution to ACP server command (#184)

Complete the model alias feature (PR #138) by adding support to
the ACP server command. This ensures consistent model alias
resolution (e.g., 'sonnet' -> 'anthropic/claude-sonnet-4-20250514')
across all CLI entry points.

This was the only missing piece from the 10 open CLI PRs, as all
other features were already implemented in the current codebase:
- PR #155: Tab completion setup on first run
- PR #153: Valid JSONL with full event data
- PR #151: Man page generation command
- PR #138: Model alias shortcuts (now complete)
- PR #137: Consistent provider casing
- PR #135: --log-level flag
- PR #134: Actual write permission check
- PR #133: Binary location from PATH
- PR #130: Searched paths in ripgrep debug
- PR #129: Valid JSON output on errors

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt

cortex-cli/src/acp_cmd.rs

@@ -5,6 +5,7 @@
 
 use anyhow::Result;
 use clap::Parser;
+use cortex_common::resolve_model_alias;
 use std::net::SocketAddr;
 use std::path::PathBuf;
 
@@ -53,7 +54,8 @@ impl AcpCli {
         }
 
         if let Some(model) = &self.model {
-            config.model = model.clone();
+            // Resolve model alias (e.g., "sonnet" -> "anthropic/claude-sonnet-4-20250514")
+            config.model = resolve_model_alias(model).to_string();
         }
 
         // Decide transport mode