v0.6.3

All behaviour fixes below ship in itasca-mcp-bridge 0.4.4 and reach end
users through the bridge's self-upgrade on next start(); they are
restated here per this changelog's convention because users perceive
them as itasca-mcp behaviour.

Fixed

• Defining FISH inside an async task no longer wedges the bridge. A
  multi-line itasca.command() containing fish define ... end was
  split line by line, so the lone fish define dropped the engine
  console into interactive FISH mode with the whole bridge unreachable
  until someone typed end in the GUI. Definition blocks (fish define / fish operator / legacy bare define) now survive
  splitting as one command.
• A model new / model restore inside a multi-line command batch no
  longer makes the bridge unreachable and tasks uninterruptible for the
  rest of the call. Those commands clear the engine's cycle-callback
  registry — the sole source of busy-time reachability (status polls,
  execute_code interleaving, interrupt). Batches are now split on the
  execute_code path too, and the re-registration hook detects resets
  on any line of a command, not just the first. Verified equally
  load-bearing on PFC 6 and PFC 7.
• Interrupting a task on PFC 6 now reports interrupted instead of
  failed. PFC 6 wraps the interrupt exception opaquely; the
  classifier now falls back to the task's pending interrupt flag.
• A live itasca_execute_code during a cycling task no longer
  silently stops the run on PFC 6. The console-capture machinery
  issued a show-message keyword PFC 6 rejects, and a command
  complaint inside the cycle callback aborts the running model cycle;
  capture commands executing in the callback now omit the keyword.
• Scripts that rebind itasca through an intermediate variable (_it = itasca) now get an explicit warning in the task/snippet output
  instead of a silently unsplit batch that can stall the bridge — the
  splitter cannot statically prove such receivers alias itasca.

Documentation

• itasca_execute_task / itasca_execute_code docstrings explain
  multi-line command normalization: batches are split to one engine
  call per command when itasca.command is reached through its import
  name, and which rebinding shapes bypass the mechanism.