agent evaluate: sort agent actions by quality using Vec::sort_by with LLM

Yes, really. Rust's stdlib sort_by with an LLM pairwise comparator.
Each comparison is an API call asking "which action was better?"

Sample N actions per agent type, throw them all in a Vec, sort.
Where each agent's samples cluster = that agent's quality score.
Reports per-type average rank and quality ratio.

Supports both haiku (fast/cheap) and sonnet (quality) as comparator.

Usage: poc-memory agent evaluate --samples 5 --model haiku

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

poc-memory/src/main.rs

@@ -565,6 +565,16 @@ enum AgentCmd {
         #[arg(long, default_value_t = 10)]
         count: usize,
     },
+    /// Evaluate agent quality by LLM-sorted ranking
+    #[command(name = "evaluate")]
+    Evaluate {
+        /// Samples per agent type
+        #[arg(long, default_value_t = 5)]
+        samples: usize,
+        /// Model to use for comparison (haiku or sonnet)
+        #[arg(long, default_value = "haiku")]
+        model: String,
+    },
 }
 
 #[derive(Subcommand)]
@@ -785,6 +795,7 @@ fn main() {
                 => cli::agent::cmd_fact_mine(&path, batch, dry_run, output.as_deref(), min_messages),
             AgentCmd::FactMineStore { path } => cli::agent::cmd_fact_mine_store(&path),
             AgentCmd::ReplayQueue { count } => cli::agent::cmd_replay_queue(count),
+            AgentCmd::Evaluate { samples, model } => cli::agent::cmd_evaluate_agents(samples, &model),
         },
 
         // Admin