Fork fix: the SDIO wedge is FIXED (esp-hosted-mcu #167)

Root cause (verified against our exact IDF tree, not the community guess):
the "258" in "sdio_write_task: Failed to send data: 258" is NOT a timeout
(that is 263). 258 = 0x102 = ESP_ERR_INVALID_ARG. On the ESP32-P4, block-
mode CMD53 writes require the SOURCE buffer to be 64-byte (cache-line)
aligned; the IDF sdmmc driver rejects a misaligned source with INVALID_ARG
BEFORE any bus activity. esp_hosts write loop then declares "Unrecoverable
host sdio state" and reboots the whole P4. The audio TX payload is not
64-aligned, so streaming mic audio wedged on the very FIRST frame (which is
exactly what we saw: listening -> instant Failed to send -> reboot).

This also explains why buffer/queue/clock/retry tuning all did nothing: the
write never reached the bus. And why our symptom was instant, not after
~100 writes (the community block-mode-desync theory) — it is the first
misaligned buffer, every time.

Fix: vendored esp_hosted 2.12.11 as an editable local component (overrides
the registry copy) and bounce a misaligned TX payload through one aligned
DMA scratch buffer in hosted_sdio_write_block (port_esp_hosted_host_sdio.c).
TX is serialized by the bus lock so a single static bounce buffer is safe;
freed in hosted_sdio_deinit. Host-only change — no C6 reflash.

VERIFIED ON HARDWARE (autonomous self-test): 40s of continuous mic-audio
upstream streaming — the traffic that previously wedged on the first frame
— ran clean, zero timeouts, zero reboots. A guarded SDIO_TX_SELFTEST harness
is kept (compiled out) for future SDIO stress testing.

Credit: root cause + patch designed via multi-agent investigation; the
precise 258=INVALID_ARG decode (correcting the upstream community timeout
assumption) came from checking our actual esp_err.h.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

firmware/components/esp_hosted/common/proto/README.md

@@ -0,0 +1,53 @@
+# About Proto Files
+
+
+## Protobuf Submodule
+
+[protobuf-c](https://github.com/protobuf-c/protobuf-c) is open source code used as submodule in ESP-Hosted-FG in directory `../protobuf-c/`
+If this directory is empty, please run
+```sh
+$ cd esp-hosted
+$ git submodule update --init --recursive
+```
+
+## Files
+
+- `esp_hosted_rpc.proto`
+  - This is Ready-To-Use protobuf file which has messages for Request / Response / Events to communicate between Host and ESP
+  - User can add his own message field in `.proto` file and generate respective C files using 'protoc'
+
+- `esp_hosted_rpc.pb-c.c` & `esp_hosted_rpc.pb-c.h`
+  - Ready-To-Use Source Generated files using `esp_hosted_rpc.proto`
+  - These files also cached which was generated with current `esp_hosted_rpc.proto` file for easy use (No need to generate again)
+  - If any addition or modifications `esp_hosted_rpc.proto` done, these files need to be re-generated
+
+
+## Generate esp_hosted_rpc.pb-c.c & esp_hosted_rpc.pb-c.h
+
+If you want to add or modify existing set of RPC procedures supported, you need to modify `esp_hosted_rpc.proto` as needed and build it to generate new set of `esp_hosted_rpc.pb-c.c` & `esp_hosted_rpc.pb-c.h`.
+For this, third party software for protobuf C compiler is needed to be installed
+- Debian/Ubuntu
+  - sudo apt install protobuf-c-compiler
+- Mac OS
+  - brew install protobuf protobuf-c
+- Windows
+  - check https://github.com/protobuf-c/protobuf-c
+
+`protoc --c_out` always needs the `protoc-gen-c` plugin from protobuf-c, so both protoc and protobuf-c must be present (on macOS these are separate Homebrew formulas, hence both are listed above).
+
+This software might only be needed on development environment, Once esp_hosted_rpc.pb-c.c & esp_hosted_rpc.pb-c.h files are generated, could also be uninstalled (no more needed).
+
+##### Steps to generate
+```sh
+$ cd <path/to/esp_hosted_fg>/common/proto
+$ protoc esp_hosted_rpc.proto --c_out=.
+```
+
+## Add new RPC message
+To send an new RPC request/response
+<TBD>
+1. Add C function in `host/host_common/commands.c`
+2. Create python binding in `host/linux/host_control/python_support/commands_map_py_to_c.py` and its python function in `host/linux/host_control/python_support/commands_lib.py`.
+3. Add ESP side C function in `esp/esp_driver/network_adapter/main/slave_commands.c`, respective to python function, to handle added message field.
+
+User can test added functionality using `host/linux/host_control/python_support/test.py`.