[contursofran]

Fixes #745

Change

• internal/app/frame.go: TerminalNotRunningLine and the NotRunning case of terminalLine are gone. The grid stays and is dimmed (staleOpacity) while the connection is not live. That check is now gridDimmed(), so tests can check it. The "terminal unavailable" and incompatible-core lines stay.
• Tests: TestTerminalLinesUseTheirTokens now checks that no line shows and the grid is dimmed. The new test TestAnEndedTerminalShowsADimmedGridAndNoLine covers the drawn slot. The "finished" case left TestTerminalSlotShowsWhyItIsNotRunning. The hidden-window test waits for the state, not the line.
• Docs: Terminal.md States, new D290; the line part of D80 is marked "replaced by D290".

New shell tab in NotRunning

I did not fix this; the cause is not proven. See the PR comment / report: Conn.attachFailed sets NotRunning for not_found/finished/machine_unknown and gives up until a "restarted" event. It sets NotRunning with a retry for any other attach error or a stream that ends. A fresh grid draws a cursor even with no output, so a failed first attach looks like a live tab.

Pre-check

1. Tests: with the NotRunning case put back, TestAnEndedTerminalShowsADimmedGridAndNoLine and TestTerminalLinesUseTheirTokens failed.
2. Plan: all brief items done; the new-tab cause is reported, not fixed.
3. Contract: D290; no ids changed besides the removed const.
4. Up to date: merged origin/main; no other open PR touches frame.go.
5. Diff read: no leftovers.
6. Coverage: issue lines 1–2 done; line 3 is reported (see above).
7. Duties: the dim stays in buildTerminal through gridDimmed.
8. Evidence: no screenshot. The visible change only removes text, and the unit tests check that no line shows. No e2e test refers to the line.

scripts/check.sh: ok.