Remove flock mode (superseded by studio)

Flock mode has been superseded by the studio multi-agent workspace manager.

Changes:
- Remove g3-ensembles crate entirely
- Remove --project, --flock-workspace, --segments, --flock-max-turns CLI flags
- Remove run_flock_mode() from autonomous.rs
- Remove flock-related tests from cli_integration_test.rs
- Update README.md, docs/architecture.md, analysis/memory.md
- Delete docs/FLOCK_MODE.md

crates/g3-cli/src/autonomous.rs

@@ -1,4 +1,4 @@
-//! Autonomous mode for G3 CLI - coach-player feedback loop and flock mode.
+//! Autonomous mode for G3 CLI - coach-player feedback loop.
 
 use anyhow::Result;
 use sha2::{Digest, Sha256};
@@ -694,37 +694,6 @@ fn print_panic_report(
     output.print(&"=".repeat(60));
 }
 
-/// Run flock mode - parallel multi-agent development
-pub async fn run_flock_mode(
-    project_dir: PathBuf,
-    flock_workspace: PathBuf,
-    num_segments: usize,
-    max_turns: usize,
-) -> Result<()> {
-    let output = SimpleOutput::new();
-
-    output.print("");
-    output.print("🦅 G3 FLOCK MODE - Parallel Multi-Agent Development");
-    output.print("");
-    output.print(&format!("📁 Project: {}", project_dir.display()));
-    output.print(&format!("🗂️  Workspace: {}", flock_workspace.display()));
-    output.print(&format!("🔢 Segments: {}", num_segments));
-    output.print(&format!("🔄 Max Turns per Segment: {}", max_turns));
-    output.print("");
-
-    let config = g3_ensembles::FlockConfig::new(project_dir, flock_workspace, num_segments)?
-        .with_max_turns(max_turns);
-
-    let mut flock = g3_ensembles::FlockMode::new(config)?;
-
-    match flock.run().await {
-        Ok(_) => output.print("\n✅ Flock mode completed successfully"),
-        Err(e) => output.print(&format!("\n❌ Flock mode failed: {}", e)),
-    }
-
-    Ok(())
-}
-
 fn print_final_report(
     output: &SimpleOutput,
     agent: &Agent<ConsoleUiWriter>,