Scaffolding: ZMK module structure, Kconfig, DTS, behavior driver

- zephyr/module.yml with dts_root for dt-bindings
- Kconfig: STENO_ENGINE, dict selection (Plover/Lapwing/test),
  MPHF toggle, Unicode modes, history size, multi-stroke timeout
- DTS behavior binding (one_param, steno key index)
- behavior_steno.c: chord accumulation, all-up detection,
  multi-stroke buffering with timeout, star undo, formatter pipeline,
  3-way dict dispatch (split/MPHF/simple trie)
- dict_embed.S: .incbin from generated header path
- steno_keys.h: 23-key layout, bit positions matching compiler

README.md

@@ -0,0 +1,66 @@
+# zmk-steno-engine
+
+Clean-room stenography engine for [ZMK Firmware](https://zmk.dev). Dictionary-based lookup with multi-stroke support, optimized for nRF52840 flash constraints.
+
+**Status:** Early development — basic single/multi-stroke lookup works, formatter not yet implemented.
+
+## Features
+
+- Standard 23-key steno layout
+- Sorted-array dictionary with binary search lookup
+- Multi-stroke support with configurable timeout
+- All-up chord detection
+- HID keyboard output (ASCII)
+- Build-time dictionary compilation from Plover JSON
+- Test dictionary included for development
+
+## Building
+
+Add as a ZMK module in your `west.yml`:
+
+```yaml
+manifest:
+  remotes:
+    - name: zmk-steno-engine
+      url-base: https://github.com/afiqzudinhadi
+  projects:
+    - name: zmk-steno-engine
+      remote: zmk-steno-engine
+      revision: optimize-dict
+```
+
+Enable in your `.conf`:
+
+```
+CONFIG_STENO_ENGINE=y
+```
+
+Use in your keymap:
+
+```dts
+#include <dt-bindings/zmk/steno_keys.h>
+
+/ {
+    keymap {
+        steno_layer {
+            bindings = <
+                &steno STENO_SL  &steno STENO_TL  &steno STENO_PL  ...
+            >;
+        };
+    };
+};
+```
+
+## Dictionary Compiler
+
+```bash
+# Compile test dictionary
+python3 tools/compile_simple.py dicts/test.json -o steno_dict.bin --stats
+
+# Compile Plover dictionary (trimmed)
+python3 tools/compile_simple.py plover-main.json -o steno_dict.bin --max-entries 120000 --stats
+```
+
+## License
+
+[PolyForm Noncommercial 1.0.0](LICENSE)