* fix(backend): prefer local copilot CLI over npx at launch
IsInstalled probed the copilot binary for the UI badge but launch always
ran `npx -y @github/copilot`, paying an npm registry round-trip every
start — minutes behind a private registry. Reuse the env-correct binary
check (standalone LookPath, SSH preflight probe) so when copilot is on
PATH the lifecycle runs it directly; containerized runtimes keep npx.
* fix(backend): make SSH native-binary probe non-fatal on transport error
The native-binary probe is an optimisation, not a requirement. A transient
SSH transport error (MaxSessions, reset) made "Verifying agent binary"
abort the launch, blaming copilot before npx was tried. Treat probe
transport errors as a miss and fall through to the required default-command
probe, which reports failures with proper context. Also call
NativeBinaryName() once.
* fix(backend): clear stale native-binary metadata before SSH probe
A pre-existing or stale MetadataKeyNativeBinary in req.Metadata could make
the command builder prefer copilot --acp on an npx-only host even when this
probe misses. Clear it up front so only a positive probe re-sets it.
* refactor(backend): use resolved RuntimeName for native-binary check
buildExecutionFromInstance re-derived the runtime from req.ExecutorType
while promoteWorkspaceExecution read execution.RuntimeName. Use the already
resolved execution.RuntimeName (set from rt.Name()) in both, so the two call
sites are consistent.
* fix(backend): reflect local copilot CLI in profile command preview
The profile setup command preview always rendered `npx -y @github/copilot`
because PreviewAgentCommand built the command without the native-binary
probe. The preview is not bound to an executor, so assume the default
standalone host and probe PATH (mirroring the standalone launch path): show
`copilot --acp` when the CLI is installed, npx otherwise.