build: replace argument dispatch and retain source-bound verification

Replace argument recovery with direct build targets. Run host, target,
board, coverage, Miri and selected Kani checks while retaining source
identities, logs and artifacts, including failed attempts.

Keep the PID proof diagnostic exception explicit and match its exact
identity alongside passing contract assertions and covers.

Validation: final-source verification matrix, assembled workflow tests
and documentation build.

firmware/README.md

@@ -11,17 +11,15 @@ firmware/
 └── scripts/    packaging, analysis, and coverage helpers
 ```
 
-This workspace owns its Makefile. From this directory, list its commands with:
+List commands from this directory:
 
 ```sh
 make help
 ```
 
-From the repository root, the firmware path is a direct Cargo proxy. For
-example, `make firmware -- test --workspace --locked --offline` runs the host
-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.
+Run Cargo directly from this directory. Build and package every supported board
+with `make -C boards build`, or one with `make -C boards/<board> build`.
+The workspace pins Rust 1.90.0. See
+[development checks](../docs/src/development.md) for the supported workflows.
 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.