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/esp-hal-procmacros/Cargo.toml

@@ -0,0 +1,88 @@
+# 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 = "2021"
+rust-version = "1.76.0"
+name = "esp-hal-procmacros"
+version = "0.15.0"
+build = false
+autolib = false
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
+description = "Procedural macros for esp-hal"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/esp-rs/esp-hal"
+
+[package.metadata.docs.rs]
+features = [
+    "embassy",
+    "has-ulp-core",
+    "interrupt",
+    "ram",
+    "is-ulp-core",
+]
+
+[lib]
+name = "esp_hal_procmacros"
+path = "src/lib.rs"
+proc-macro = true
+
+[dependencies.darling]
+version = "0.20.10"
+
+[dependencies.document-features]
+version = "0.2.10"
+
+[dependencies.litrs]
+version = "0.4.1"
+
+[dependencies.object]
+version = "0.36.5"
+features = [
+    "read_core",
+    "elf",
+]
+optional = true
+default-features = false
+
+[dependencies.proc-macro-crate]
+version = "3.2.0"
+
+[dependencies.proc-macro-error2]
+version = "2.0.1"
+
+[dependencies.proc-macro2]
+version = "1.0.89"
+
+[dependencies.quote]
+version = "1.0.37"
+
+[dependencies.syn]
+version = "2.0.87"
+features = [
+    "extra-traits",
+    "full",
+]
+
+[features]
+embassy = []
+enum-dispatch = []
+has-lp-core = ["dep:object"]
+has-ulp-core = ["dep:object"]
+interrupt = []
+is-lp-core = []
+is-ulp-core = []
+ram = []
+rtc_slow = []