Remove flock mode (superseded by studio)

Flock mode has been superseded by the studio multi-agent workspace manager.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

@@ -29,7 +29,7 @@ use clap::Parser;
 
 use accumulative::run_accumulative_mode;
 use agent_mode::run_agent_mode;
-use autonomous::{run_autonomous, run_flock_mode};
+use autonomous::run_autonomous;
 use interactive::run_interactive;
 use project_files::{combine_project_content, read_agents_config, read_project_memory, read_project_readme};
 use simple_output::SimpleOutput;
@@ -39,19 +39,6 @@ use utils::{initialize_logging, load_config_with_cli_overrides, setup_workspace_
 pub async fn run() -> Result<()> {
     let cli = Cli::parse();
 
-    // Check if flock mode is enabled
-    if let (Some(project_dir), Some(flock_workspace), Some(num_segments)) =
-        (&cli.project, &cli.flock_workspace, cli.segments)
-    {
-        return run_flock_mode(
-            project_dir.clone(),
-            flock_workspace.clone(),
-            num_segments,
-            cli.flock_max_turns,
-        )
-        .await;
-    }
-
     if cli.codebase_fast_start.is_some() {
         print!("codebase_fast_start is temporarily disabled.");
         std::process::exit(1);