feat(firmware): validate configuration and migrate sensor-driven flight APIs

Validate configuration through its owning schemas and keep board
declarations separate from shared F722 resource ownership. Bound USB
transitions, isolate transport failures and retain restart-only activation.

Migrate navigation and flight consumers with the sensor and schema
contracts. Require explicit installation data and synchronous output
authority; board motor outputs remain inhibited.

Validation: assembled-prefix host tests, strict Clippy, platform/USB tests
and both ARM release builds. Final-source coverage and scoped Miri/Kani
evidence are retained separately from hardware qualification.

firmware/README.md

@@ -1,15 +1,13 @@
 # Firmware
 
-This directory is the Kaptan flight-controller firmware workspace. It owns the
-Rust workspace manifest, board declarations, platform implementation, reusable
-firmware crates and firmware scripts.
+Kaptan flight-controller firmware workspace.
 
 ```text
 firmware/
-├── boards/     immutable board declarations and linker layouts
+├── boards/     board hardware declarations and entry points
 ├── libs/       reusable no_std firmware crates
-├── platforms/  hardware platform composition
-├── tools/      firmware development tooling
+├── platforms/  hardware composition, configuration and linker layouts
+├── tools/      local configuration and telemetry tools
 └── scripts/    packaging, analysis, and coverage helpers
 ```
 
@@ -25,3 +23,5 @@ test suite. Build and package every supported board with
 `make firmware/boards`, or select one board by its directory path.
 Run `make firmware clippy` for Rust lints and `make firmware docs` for API
 documentation with warnings denied.
+The board images do not yet run the flight runtime or implement motor drivers.
+Motor pins are inhibited at startup. Physical flight has not been qualified.