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/zerocopy/Cargo.toml.std

@@ -0,0 +1,58 @@
+[package]
+name = "std-deps"
+version = "0.0.0"
+edition = "2021"
+publish = false
+
+# This manifest exists solely to force `cargo vendor` to vendor dependencies
+# required by `std` when building with `-Zbuild-std[=core]`. When running
+# `cargo vendor`, make sure to include this manifest using `--sync`.
+#
+# See: https://github.com/rust-lang/wg-cargo-std-aware/issues/23
+
+[workspace]
+
+[dependencies]
+# Dependencies from std/Cargo.toml and transitive deps from library/Cargo.lock
+addr2line = { version = "=0.25.1", default-features = false }
+adler2 = { version = "=2.0.1", default-features = false }
+cc = { version = "=1.2.0", default-features = false }
+cfg-if = { version = "=1.0.4", default-features = false }
+dlmalloc = { version = "=0.2.11", default-features = false }
+foldhash = { version = "=0.2.0", default-features = false }
+fortanix-sgx-abi = { version = "=0.6.1", default-features = false }
+getopts = { version = "=0.2.24", default-features = false }
+gimli = { version = "=0.32.3", default-features = false }
+hashbrown = { version = "=0.16.1", default-features = false }
+hermit-abi = { version = "=0.5.2", default-features = false }
+libc = { version = "=0.2.178", default-features = false }
+memchr = { version = "=2.7.6", default-features = false }
+miniz_oxide = { version = "=0.8.9", default-features = false }
+moto-rt = { version = "=0.16.0", default-features = false }
+object = { version = "=0.37.3", default-features = false }
+r-efi = { version = "=5.3.0", default-features = false }
+r-efi-alloc = { version = "=2.1.0", default-features = false }
+rand = { version = "=0.9.2", default-features = false }
+rand_core = { version = "=0.9.3", default-features = false }
+rand_xorshift = { version = "=0.4.0", default-features = false }
+rustc-demangle = "=0.1.26"
+rustc-literal-escaper = { version = "=0.0.7", default-features = false }
+shlex = { version = "=1.3.0", default-features = false }
+unwinding = { version = "=0.2.8", default-features = false }
+vex-sdk = { version = "=0.27.1", default-features = false }
+wasi-snapshot-preview1 = { package = "wasi", version = "=0.11.1+wasi-snapshot-preview1", default-features = false }
+wasi-p2 = { package = "wasi", version = "=0.14.4+wasi-0.2.4", default-features = false }
+windows-link = { version = "=0.2.1", default-features = false }
+windows-sys = { version = "=0.60.2", default-features = false }
+windows-targets = { version = "=0.53.5", default-features = false }
+wit-bindgen = { version = "=0.45.1", default-features = false }
+
+# Windows targets dependencies (transitive via windows-targets)
+windows_aarch64_gnullvm = { version = "=0.53.1", default-features = false }
+windows_aarch64_msvc = { version = "=0.53.1", default-features = false }
+windows_i686_gnu = { version = "=0.53.1", default-features = false }
+windows_i686_gnullvm = { version = "=0.53.1", default-features = false }
+windows_i686_msvc = { version = "=0.53.1", default-features = false }
+windows_x86_64_gnu = { version = "=0.53.1", default-features = false }
+windows_x86_64_gnullvm = { version = "=0.53.1", default-features = false }
+windows_x86_64_msvc = { version = "=0.53.1", default-features = false }