feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/byte-slice-cast/.cargo-checksum.json

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vendor/byte-slice-cast/.cargo_vcs_info.json

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vendor/byte-slice-cast/CHANGELOG.md

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+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html),
+specifically the [variant used by Rust](http://doc.crates.io/manifest.html#the-version-field).
+
+## [1.2.3] - 2025-03-03
+### Changed
+- Fix tests for Rust 1.81.
+- Declare Rust 1.51 as MSRV.
+
+## [1.2.2] - 2022-10-28
+### Changed
+- Fix a couple of clippy warnings in the tests.
+
+## [1.2.1] - 2022-02-25
+### Changed
+- Make trait methods `#[inline]`. This allows the compiler to make the call a
+  no-op in many cases.
+
+## [1.2.0] - 2021-10-19
+### Added
+- Trait impls for converting between `&[[T; N]]` and `&[u8]` for specific `T`.
+
+## [1.1.0] - 2021-09-16
+### Added
+- `ToByteSlice` and `ToMutByteSlice` impl for `&[()]`. This always produces an
+  empty byte slice.
+
+## [1.0.0] - 2020-10-13
+### Removed
+- Support for casting between `Vec<T>` and `Vec<u8>`. This was actually
+  unsound as the alloc trait requires that memory is deallocated with exactly
+  the same alignment as it was allocated with.
+
+### Fixed
+- `usize` tests on 16/32 bit architectures.
+
+### Changed
+- Various documentation improvements.
+
+## [0.3.5] - 2019-12-22
+### Changed
+- Improve documentation and examples
+
+### Fixed
+- Fix running of tests on 16/32 bit architectures
+
+## [0.3.4] - 2019-11-11
+### Added
+- Support for casting between `Vec<T>` and `Vec<u8>`
+
+## [0.3.3] - 2019-11-02
+### Added
+- Support for `usize` and `isize`
+
+## [0.3.2] - 2019-07-26
+### Changed
+- Add `no_std` support
+- Migrate to 2018 edition
+
+## [0.3.1] - 2019-06-05
+### Fixed
+- Casting of empty slices works correctly now instead of failing with an
+  alignment mismatch error.
+
+## [0.3.0] - 2019-05-11
+### Added
+- The `Error` type now implements `Clone`.
+
+### Changed
+- `AsByteSlice::as_byte_slice` and `ToByteSlice::to_byte_slice` were changed
+  to always return `&[u8]` instead of `Result<&[u8], Error>`.
+- `AsMutByteSlice::as_mut_byte_slice` and `ToMutByteSlice::to_mut_byte_slice`
+  were changed to always return `&mut [u8]` instead of `Result<&mut [u8],
+  Error>`.
+- The `Display` impl for `Error` now produces more detailed error messages.
+- The variants of the `Error` enum were renamed.
+
+## [0.2.0] - 2018-06-01
+### Changed
+- Major refactoring of how the traits work. It is now possible to work
+  directly on `AsRef<[T]>` and `AsMut<[T]>`, e.g. on `Vec<T>` and `Box<[T]>`.
+
+### Added
+- Trait impls for i128 and u128.
+
+## [0.1.0] - 2017-08-14
+- Initial release of the `byte-slice-cast` crate.
+
+[Unreleased]: https://github.com/sdroege/byte-slice-cast/compare/1.2.3...HEAD
+[1.2.3]: https://github.com/sdroege/byte-slice-cast/compare/1.2.2...1.2.3
+[1.2.2]: https://github.com/sdroege/byte-slice-cast/compare/1.2.1...1.2.2
+[1.2.1]: https://github.com/sdroege/byte-slice-cast/compare/1.2.0...1.2.1
+[1.2.0]: https://github.com/sdroege/byte-slice-cast/compare/1.1.0...1.2.0
+[1.1.0]: https://github.com/sdroege/byte-slice-cast/compare/1.0.0...1.1.0
+[1.0.0]: https://github.com/sdroege/byte-slice-cast/compare/0.3.5...1.0.0
+[0.3.5]: https://github.com/sdroege/byte-slice-cast/compare/0.3.4...0.3.5
+[0.3.4]: https://github.com/sdroege/byte-slice-cast/compare/0.3.3...0.3.4
+[0.3.3]: https://github.com/sdroege/byte-slice-cast/compare/0.3.2...0.3.3
+[0.3.2]: https://github.com/sdroege/byte-slice-cast/compare/0.3.1...0.3.2
+[0.3.1]: https://github.com/sdroege/byte-slice-cast/compare/0.3.0...0.3.1
+[0.3.0]: https://github.com/sdroege/byte-slice-cast/compare/0.2.0...0.3.0
+[0.2.0]: https://github.com/sdroege/byte-slice-cast/compare/0.1.0...0.2.0

vendor/byte-slice-cast/Cargo.lock

@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "byte-slice-cast"
+version = "1.2.3"

vendor/byte-slice-cast/Cargo.toml

@@ -0,0 +1,45 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.51.0"
+name = "byte-slice-cast"
+version = "1.2.3"
+authors = ["Sebastian Dröge <sebastian@centricular.com>"]
+build = false
+include = [
+    "src/lib.rs",
+    "Cargo.toml",
+    "LICENSE",
+    "README.md",
+    "CHANGELOG.md",
+]
+autolib = false
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
+description = "Safely cast bytes slices from/to slices of built-in fundamental numeric types"
+readme = "README.md"
+keywords = ["no_std"]
+license = "MIT"
+repository = "https://github.com/sdroege/bytes-num-slice-cast"
+
+[features]
+default = ["std"]
+std = []
+
+[lib]
+name = "byte_slice_cast"
+path = "src/lib.rs"
+
+[dependencies]

vendor/byte-slice-cast/LICENSE

@@ -0,0 +1,23 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 Sebastian Dröge <sebastian@centricular.com>.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+

vendor/byte-slice-cast/README.md

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+# byte-slice-cast [![crates.io](https://img.shields.io/crates/v/byte-slice-cast.svg)](https://crates.io/crates/byte-slice-cast) [![Actions Status](https://github.com/sdroege/byte-slice-cast/workflows/byte-slice-cast/badge.svg)](https://github.com/sdroege/byte-slice-cast/actions) [![docs.rs](https://docs.rs/byte-slice-cast/badge.svg)](https://docs.rs/byte-slice-cast)
+
+Safely cast between byte slices and slices of another built-in fundamental number type.
+
+## LICENSE
+
+byte-slice-cast is licensed under the MIT license ([LICENSE](LICENSE) or
+http://opensource.org/licenses/MIT).
+
+## Contribution
+
+Any kinds of contributions are welcome as a pull request.
+
+Unless you explicitly state otherwise, any contribution intentionally
+submitted for inclusion in byte-slice-cast by you shall be licensed under the
+MIT license as above, without any additional terms or conditions.