refactor(agent): use agent-neutral runtime names

Assisted-by: Codex

docs/prds/0003-bottle-backend-abstraction.md

@@ -62,7 +62,7 @@ The feature is **done** when all of the following ship:
   `Bottle`) plus a `bot_bottle/backend/docker/` subpackage
   containing the `DockerBottleBackend` implementation.
 - `DockerBottleBackend.launch(plan)` returns a context manager
-  yielding a `Bottle` handle exposing `exec_claude(argv, *, tty=True)`,
+  yielding a `Bottle` handle exposing `exec_agent(argv, *, tty=True)`,
   `cp_in(host, ctr)`, and teardown on context exit.
 - Every existing `subprocess.run(["docker", ...])` call in
   `cli/start.py`, `pipelock.py`, `network.py`, `ssh.py`, and
@@ -205,7 +205,7 @@ and a Docker subpackage:
 - **`bot_bottle/cli/start.py`** — replace the inline docker
   orchestration with `backend = get_bottle_backend(); plan =
   backend.prepare(spec, stage_dir=...); with backend.launch(plan) as
-  bottle: bottle.exec_claude(...)`. The y/N preflight is rendered by
+  bottle: bottle.exec_agent(...)`. The y/N preflight is rendered by
   `plan.print(...)`.
 - **`bot_bottle/manifest.py`** — drop the `runtime` field from the
   Bottle dataclass and its validation. Existing manifests with