Fix stateful-sensor crash on GetStatus; add explicit Status API

[Nicolas Palpacuer (NickPPC)]

Summary

The viam:sensor-bundle:stateful-sensor model crash-looped on deployed machines (observed on machine Cappuccina): the module panicked with a SIGSEGV (exit code 2) and was repeatedly restarted. The model embedded resource.Named but never initialized it, so the sensor service's GetStatus RPC invoked the promoted Status method on a nil receiver. This PR fixes the crash and adds an explicit Status API so the model owns the behavior.

Changes

• resources/statefulsensor: Initialize the embedded resource.Named via name.AsNamed() (matching the sensor-monitor model), which fixes the nil-receiver panic in the GetStatus path.
• resources/statefulsensor: Drop the now-redundant name field and custom Name() method, deferring to the embedded Named.
• resources/statefulsensor: Add an explicit Status(ctx) method returning operational metadata (file_path, num_keys) instead of the empty default — distinct from Readings, which returns the stored value itself.

Testing

• Added TestStatus covering the Status API: asserts file_path/num_keys before and after a set (0 → 2 keys), and guards against the nil-receiver crash regression.
• go build ./..., go vet ./..., and gofmt all clean; full test suite passes.

Root cause

The crash signature from the machine logs:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 ...]
sensorbundle.(*sensorBundleStatefulSensor).Status(...)  <autogenerated>:1
go.viam.com/rdk/protoutils.GetStatusFromResourceServer(...)
go.viam.com/rdk/components/sensor.(*serviceServer).GetStatus(...)

resource.Named is an interface declaring Name(), DoCommand(), and Status(). The struct overrode the first two but not Status(), and the constructor left the embedded interface nil — so any GetStatus call dereferenced nil.

Claude Code Prompts Used

• "check the logs for issue with the current module on the Viam machine with part ID 5be4df6e-b9ae-4a5f-acc0-e258d51be17d"
• "create a new worktree off of origin/main"
• "yes" (apply the fix plus a GetStatus regression test)
• "Can you also add an explicit Status API if not present?"
• "commit and open a PR"

🤖 Generated with Claude Code