emrg: the feishu template reads a missing identity as an expired account #2468

What was observed

emrg/server/feishu_prompt.md is the instruction block a scheduled feishu task renders into
its prompt. Its §1 (Read) ends:

• A CLI that cannot run, or an account whose authorisation has expired, is a blocked item
  reported to the host.

That sentence names two causes of an unavailable account and gives both the same remedy: report
it blocked. There is a third cause, and it needs no one.

lark-cli resolves its identity from directories under $HOME — $HOME/Library/Application Support/lark-cli/ holds the encrypted token material and its master key, with a separate
$HOME/.lark-cli/ holding config.json and locks. An identity is therefore not a property of
the tool but of the environment the tool is started in: the same account reads missing identity
under one HOME and valid under another. A round that runs the CLI in an environment other than
the one the account was authorised in sees missing about a token that is working.

Why it matters

Two harms, and the second is the worse one.

1. The report cannot be told apart from a real expiry. The round reports blocked, the host reads
   "the account expired", and every following round says the same thing about a working account.
2. The obvious next step is a fresh authorisation. That is a change to the host's account state,
   taken on a symptom — and it does not cure the round, because a different HOME reproduces the
   symptom whatever the token says.

What the fix must satisfy

• §1 states that missing identity is a symptom rather than a cause, and says where the identity
  comes from.
• The round checks with auth status in the same environment the send will use, and reports the
  cause it read rather than the word the call printed.
• A round never starts a fresh authorisation on a single missing answer.
• The two real causes stay exactly as they are: a CLI that cannot run, and an account that
  genuinely cannot authenticate. Forbidden is unchanged, word for word.
• The new clause is pinned by tests/test_scheduler.py, which already pins the template's other
  four anchors. A clause that spans a line break is pinned after its whitespace is collapsed: a
  raw substring pin decides where the wrap falls, and can be left green by a word-level negation
  (measured on this change — a pin on start a fresh authorisation … survived Never rewritten
  to You may).

Out of scope

The CLI and its credential layout. Every path, account name and per-installation override belongs
in the task's extra_prompt and stays out of the template.