test(e2e): assert the fixture's preconditions, and say where connect stopped

[sotashimozono]

Stacked on #495.

The problem this fixes is diagnostic, not behavioural

Three different faults have been producing one message:

no shadow vault entry appeared in obsidian.json — connect command likely never fired

That collapse cost three rounds of fixing the wrong thing. The text stayed identical while its cause changed underneath: the palette was not interactive (#492), then the command might not have been registered (#493), then ConnectModal's second pane was never clicked (#495). Each fix was right; none of them could be known to be right from the message.

What now names itself

The scaffold asserts what connect depends on and throws as a fixture fault, not a product failure:

• the test private key exists — without it, auth cannot succeed;
• for the default rpc transport, a daemon binary was actually staged — without it there is nothing to connect to.

Either now reads fixture missing: … with the path and the fix, instead of surfacing as "connect is broken" in fifteen specs.

connectAndWaitForShadowVault attaches the evidence that separates the remaining two causes:

  plugin log (tail): <last 12 lines — how far connect actually got>
  visible modal buttons: <labels — whether the click landed>

Both are best-effort: a diagnostic that throws would replace the error it exists to explain.

Why this instead of another guess

The last E2E run still fails connect nearly everywhere, and I have now twice mistaken this message for a cause I could name. The honest next step is to make the run answer the question rather than to patch a fourth hypothesis into it.

Verification

tsc --noEmit green locally. No unit-test surface. No auto-merge.

Refs #429

🤖 Generated with Claude Code

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