feat(agents): named and labelled agents with optional ANSI color

Chunk 1 (schema + storage): BottleSpec, ActiveAgent, and BottleMetadata
gain label and color fields. Both docker and smolmachines backends
persist them to metadata.json on prepare and surface them in
enumerate_active_agents(). AgentProvider.provision_plan() passes
label/color through to the Claude provider, which injects them into
claude.json so claude-code displays the session name and color in its
header. Codex provider accepts and ignores the knobs.

Chunk 2 (curses modal + display): cmd_start presents a two-step curses
modal — first edit the label (first keystroke replaces the pre-fill),
then optionally pick a color. cli list active renders label with ANSI
escape codes when the terminal supports it, falling back to agent_name
when no label is set.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bot_bottle/backend/docker/prepare.py

@@ -80,6 +80,8 @@ def resolve_plan(
         started_at=datetime.now(timezone.utc).isoformat(),
         compose_project=f"bot-bottle-{slug}",
         backend="docker",
+        label=spec.label,
+        color=spec.color,
     ))
     # Clear any leftover preserve marker from a prior capability-block
     # so this fresh launch can be cleaned up at session-end unless
@@ -191,6 +193,8 @@ def resolve_plan(
         auth_token=provider.auth_token,
         host_env=dict(os.environ),
         trusted_project_path=workspace_plan.workdir,
+        label=spec.label,
+        color=spec.color,
     )
     guest_env = dict(agent_provision.guest_env)
     for key, val in agent_provision.env_vars.items():