fix(onboarding): verify bootstrap message rendered before consuming one-shot gate

[indierawk2k2]

Summary

Follow-up to Scott's PR #274 onboarding/chat work. The hatching/bootstrap prompt path was running, but BootstrapMessageInjector could consume HasInjectedFirstRunBootstrap after JavaScript merely returned "sent" without confirming the message actually rendered or the composer accepted it.

This PR hardens the injector so false-positive sends stay retryable instead of permanently suppressing the first-run hatching prompt.

Changes

• Narrow send-button discovery to the located chat composer's form/container instead of accepting broad page buttons.
• Prefer the input-associated form, then clearly-labeled send controls, then Enter fallback.
• Poll after submit for confirmation that the input cleared or the message text appears in visible transcript text.
• Return distinct retryable statuses such as sent-unverified, no-input, and no-send-button.
• Only call MarkInjected() for confirmed sent.
• Add tests proving sent-unverified does not flip HasInjectedFirstRunBootstrap, while verified sent still does.

Validation

• ./build.ps1 — PASS (Cli, Shared, WinNodeCli, WinUI)
• dotnet test ./tests/OpenClaw.Shared.Tests/OpenClaw.Shared.Tests.csproj --no-restore with OPENCLAW_REPO_ROOT set — PASS: 1465 total, 1443 succeeded, 22 skipped
• dotnet test ./tests/OpenClaw.Tray.Tests/OpenClaw.Tray.Tests.csproj --no-restore --no-build with OPENCLAW_REPO_ROOT set — PASS: 911 total, 911 succeeded, 0 skipped
• dotnet vstest ./tests/OpenClaw.Tray.Tests/bin/Debug/net10.0/OpenClaw.Tray.Tests.dll — PASS: 911 total, 911 passed
• Fresh-binary smoke after build — PASS: launched OpenClaw.Tray.WinUI.exe from this worktree with isolated OPENCLAW_TRAY_DATA_DIR; process stayed alive for 15 seconds

Note: a full dotnet test ./tests/OpenClaw.Tray.Tests/OpenClaw.Tray.Tests.csproj --no-restore build+test invocation hung in this local shell during project build output; the already-built test DLL passed via dotnet test --no-build and dotnet vstest.

Mike retest unstick command

Mike's current box already has HasInjectedFirstRunBootstrap=true, so after installing this build and before retesting first-run hatching, run:

$p="$env:APPDATA\OpenClawTray\settings.json"
$j=Get-Content $p -Raw|ConvertFrom-Json
$j.HasInjectedFirstRunBootstrap=$false
$j|ConvertTo-Json -Depth 10|Set-Content $p

This is not a reset of credentials; it only reopens the one-shot bootstrap prompt gate.