system/smf: Port SMF .c/.h files to NuttX

[FelipeMdeO]

Fixed build issues

Added example to demonstate state machine framework

Removed unused file

Improve code quality | Fix thread termination issue

Note: Please adhere to Contributing Guidelines.

Summary

This change adds the State Machine Framework (SMF) to nuttx-apps as a
self-contained, reusable library.

The SMF provides a deterministic framework for implementing flat and
hierarchical state machines, based on explicit entry, run, and exit actions.
Event handling and scheduling remain fully under application control.

The implementation is a port of the SMF originally introduced in the Zephyr
RTOS, adapted to NuttX coding conventions and build infrastructure. The library
does not perform dynamic memory allocation and is intended to be used with
statically defined state tables.

An example application is included to demonstrate correct usage.

Impact

• Adds a new optional library to nuttx-apps, enabled via Kconfig.
• No impact on existing applications when the feature is disabled.
• No changes to existing APIs or build configurations.
• No dynamic memory usage introduced.
• Architecture-independent and suitable for both hosted and embedded targets.

Testing

The change was validated using the provided SMF hierarchical state machine
(HSM) example application. Example available in:
| Prompt: State Machine Framework PSICC2 demo (HSM) │
│ Location:
│
│ -> Application Configuration │
│ -> Examples
| -> State Machine Framework PSICC2 demo

Testing was performed by enabling the SMF configuration options and building
the example for the simulator target. The example demonstrates:

• Initialization of the state machine using smf_set_initial()
• Execution of flat and hierarchical states
• State transitions triggered from run actions
• Entry and exit action sequencing
• Graceful termination using smf_set_terminate()

The example was built and executed using the sim:nsh configuration. Runtime
output was manually verified to confirm correct state transitions and expected
execution order.

No regressions were observed, and existing applications build and run
unchanged when SMF is not enabled.

[linguini1]

Looks really solid! Just some minor comments to pass the CI checks/adhere to the formatting rules. Thank you for porting this to NuttX!

By the way, the commit message's topic and the PR title should be formatted like: system/smf: Port SMF .c/.h files to NuttX

[FelipeMdeO]

Hello All, I solved the issues as requested. Thanks for the review.

[cederom]

Thank you @FelipeMdeO very useful features! :-)

Just please update select to depends on in the Kconfig as requsted by @xiaoxiang781216 :-)

[cederom]

Uhm, sorry still some build errors + Kconfig updates todo :-)

[cederom]

Very cool, thanks @FelipeMdeO, lets just wait for the CI build verificaion :-)

[cederom]

Thank you @FelipeMdeO :-) Lets just wait for the CI to complete :-)