Add reconciler and ingest modules with CLI driver

reconciler: generic resource state machine — BFS pathfinding from current
to wanted state, dependency constraints, event/periodic tick model.
reconciler_cli exercises it with simulated device/transport/stream resources.

ingest: V4L2 capture module — open device, negotiate MJPEG format, MMAP
buffer pool, capture thread with on_frame callback. start/stop lifecycle
designed for reconciler management. Transport-agnostic: caller wires
on_frame to proto_write_video_frame.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/reconciler/Makefile

@@ -0,0 +1,19 @@
+ROOT := $(abspath ../../..)
+include $(ROOT)/common.mk
+
+MODULE_BUILD = $(BUILD)/reconciler
+
+.PHONY: all clean
+
+all: $(MODULE_BUILD)/reconciler.o
+
+$(MODULE_BUILD)/reconciler.o: reconciler.c | $(MODULE_BUILD)
+	$(CC) $(CFLAGS) $(DEPFLAGS) -c -o $@ $<
+
+$(MODULE_BUILD):
+	mkdir -p $@
+
+clean:
+	rm -f $(MODULE_BUILD)/reconciler.o $(MODULE_BUILD)/reconciler.d
+
+-include $(MODULE_BUILD)/reconciler.d