Scaffold NCS firmware project structure

Sets up kvida-os as a freestanding nRF Connect SDK application for the
nRF54L15, pinned to NCS v3.4.0, with a Docker/WSL2 build environment
(toolchain-only image, NCS modules fetched into a separate volume at
first run) and placeholder module directories matching the architecture
described in the kvida meta-repo.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/prj.conf

@@ -0,0 +1,6 @@
+# Minimal base configuration so the application boots and logs.
+# Matter, Thread, power management, and other feature-specific Kconfig
+# options are added as the corresponding modules gain real implementations.
+
+CONFIG_LOG=y
+CONFIG_GPIO=y