Import ESP_UniClock (upstream 1189810)

Vendored from https://github.com/gpeter62/ESP_UniClock: the sketch
source, the web UI and the libraries the ESP8266 build needs, unpacked
from the bundled zips. Adds a PlatformIO project for the ESP-12. The
source is unchanged; local changes follow as separate commits.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

firmware/uniclock/lib/ArduinoJson/extras/fuzzing/Makefile

@@ -0,0 +1,22 @@
+# CAUTION: this file is invoked by https://github.com/google/oss-fuzz
+
+CXXFLAGS += -I../../src -DARDUINOJSON_DEBUG=1
+
+all: \
+	$(OUT)/json_fuzzer \
+	$(OUT)/json_fuzzer_seed_corpus.zip \
+	$(OUT)/json_fuzzer.options \
+	$(OUT)/msgpack_fuzzer \
+	$(OUT)/msgpack_fuzzer_seed_corpus.zip \
+	$(OUT)/msgpack_fuzzer.options
+
+$(OUT)/%_fuzzer: %_fuzzer.cpp $(shell find ../../src -type f)
+	$(CXX) $(CXXFLAGS) $< -o$@ $(LIB_FUZZING_ENGINE)
+
+$(OUT)/%_fuzzer_seed_corpus.zip: %_seed_corpus/*
+	zip -j $@ $?
+
+$(OUT)/%_fuzzer.options:
+	@echo "[libfuzzer]" > $@
+	@echo "max_len = 256" >> $@
+	@echo "timeout = 10" >> $@