refactor: scrub stale /actions + ActionsController comment refs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016RVNkdUCoxqgGVVhUoApVp

Author: cailmdaley

lib/shuttle/lifecycle_service.ex

@@ -4,7 +4,7 @@ defmodule Shuttle.LifecycleService do
   awaiting role by writing the felt document (`accept` / `resume`).
 
   Both the `/api/v1/lifecycle` endpoint (operator / shuttle-ctl) and the
-  `/api/v1/actions/invoke` kanban path go through here, so an accept behaves
+  `/api/v1/transition` kanban path go through here, so an accept behaves
   identically regardless of which gesture triggered it. The work is:
 
     1. Run the transition *through the Poller* (`Poller.lifecycle_transition/3`)

lib/shuttle/poller.ex

@@ -3059,7 +3059,7 @@ defmodule Shuttle.Poller do
   # command, the host directory it ran in, the exit status, and trimmed
   # stderr. felt's own stderr for a nonexistent store can be empty (it just
   # finds no index), which previously bubbled up as a BLANK `{:error, ""}` →
-  # an undiagnosable 500 at the ActionsController boundary. Including the host
+  # an undiagnosable 500 at the HTTP boundary. Including the host
   # path names the actual fault — typically a felt-store path that doesn't
   # exist on this machine (a foreign absolute path registered by another
   # host's portolan).

lib/shuttle/transition.ex

@@ -32,8 +32,7 @@ defmodule Shuttle.Transition do
        relayed response's `origin`. Terminating in one hop: a fiber has exactly
        one owner, and the owner never re-forwards.
 
-  Both this service's `/transition` endpoint and the legacy `/actions/invoke`
-  endpoint share `invoke/2` and `http_error/1`, so the invoke pipeline and its
+  This service's `/transition` endpoint uses `invoke/2` and `http_error/1`, so the invoke pipeline and its
   status mapping have a single implementation.
   """
 
@@ -92,7 +91,7 @@ defmodule Shuttle.Transition do
 
   @doc """
   The invoke pipeline: validate the action id, confirm it is available for the
-  fiber right now, then perform the mutation. Shared with `/actions/invoke`.
+  fiber right now, then perform the mutation.
   """
   @spec invoke(String.t(), String.t()) :: :ok | {:error, term()}
   def invoke(fiber_id, action) do