the daemon's own file readers open their subject whatever it is, so a FIFO blocks the daemon forever #2073

What is wrong

#2062 taught the three file tools (read, write, edit) to ask what they are
opening, because an open is not a read: on a FIFO a read blocks until a writer
appears, on a socket until a connection does, and a device never ends. The predicate is
emrg.tools.base.special_file_kind (a whitelist: S_ISREG or nothing).

The guard stops at the tool layer. The daemon has five readers of its own that open a
path the agent or the client names, and none of them asks:

Each wraps its read in except (OSError, UnicodeDecodeError), which cannot bound this: a
FIFO raises nothing, it simply never returns. The read is synchronous, inside a coroutine
the daemon awaits on its event loop, so the block is the whole daemon — every session,
the scheduler and the evolution loop with it — and the only recovery is a restart, which
belongs to the host.

The workspace listing makes the client's route ordinary rather than exotic:
_handle_list_files types every entry that is not a directory as "file", so a named
pipe in a workspace is offered in the file tree and one click on it wedges the daemon.

Measurement

Checkout measured: /Users/argszero/.emrg/evolution/emrg on master 63ee3a54
(emrg.__file__ printed inside the probe). Each call in its own process, killed by the
parent's cap.

open(<fifo>, "r")                      -> DID NOT RETURN within 6s
EmrgServer._cap_memory_index(<fifo>)   -> DID NOT RETURN within 25s

The control, on the same fixture: the three tools answer the FIFO in milliseconds with
Error: … is a FIFO (named pipe), not a regular file (#2062).

What fixes it

One predicate at five readers, and each reader takes the branch it already has for a file
it cannot read — skip for the two scanners, the existing _unreadable_index_notice for
the two index carriers, an error frame for the client handler. No new concept: the rule is
special_file_kind's, which this repo already states once.

read_file, list_memories and the system prompt all answer a non-regular subject
instead of entering it.

The failure is the same one #2062 measured at the tools, at the readers that were not
in that change.