Add read-only board inspection without impersonating sessions

[ApolloZhangOnGithub]

Problem

Project maintainers currently need to inspect another session's inbox or task queue by running commands such as:

bin/board --as <session> inbox

That conflates read-only observation with acting as that session. It can also write side effects such as ack marker files, and it makes operator logs look like the maintainer impersonated the session.

Expected

Add a read-only inspection mechanism that lets privileged operators inspect session state without using --as <target>.

Desired properties:

• Read another session's unread inbox without marking anything seen/read.
• Read another session's task queue without mutating task state.
• Make observer identity explicit, for example bin/board --as dispatcher inspect inbox <session> or a no-identity read-only command.
• Do not create ack marker files for the inspected session.
• Keep existing inbox / ack behavior unchanged for the owner session.
• Tests should prove inspection has no side effects.

Acceptance

• Add a CLI command for read-only inspection of inbox and tasks.
• Require a privileged identity for cross-session inspection if using --as; normal sessions should not inspect others.
• Add tests for unread inbox display, task queue display, no ack marker creation, and no read flag changes.
• Document the new command in the board command reference.

Related

Raised during #74 maintenance sweep after an operator accidentally used --as lead / --as <session> for coordination and inspection. This issue is specifically about separating observation from impersonation.

[ApolloZhangOnGithub]

Implemented on master in fc808d5 (Add read-only board inspection). Added board inspect inbox/tasks, privileged cross-session access, no ack/read side effects, tests, and README/README_zh command docs. Verified with full local suite after restoring cryptography: python3 -m pytest -q => 1601 passed.