rename PyPI package to pydcp

`dcp-protocol` was RAS-syndrome (Protocol Protocol) — I called it out for
the GitHub org name then forgot for PyPI. `pydcp` follows the Python
convention (pyserial/pyyaml/pymongo) and is shorter.

Import name is unchanged: `import dcp`. The protocol name DCP is also
unchanged. Only the on-PyPI distribution name moves.

Bare `dcp` on PyPI is taken by an unrelated Distributive Network package
(Distributed Compute Protocol) and is unrecoverable.

Author: WaylandYang

.github/announce/zhihu.md

@@ -94,7 +94,7 @@ UART / MQTT / BLE / USB-CDC 同一份固件,只换 transport 类。**从原型
 ### 试一下
 
 ```bash
-pip install dcp-protocol[mcp,serial]
+pip install pydcp[mcp,serial]
 dcp serve examples/lamp_manifest.yaml --simulator
 # 或者你有 ESP32:
 # 烧 firmware/esp32/examples/lamp/lamp.ino

pyproject.toml

@@ -1,7 +1,7 @@
 [project]
-name = "dcp-protocol"
+name = "pydcp"
 version = "0.3.0"
-description = "Device Context Protocol — bridge between LLM agents and physical devices. Import as `dcp`."
+description = "Device Context Protocol — Python reference implementation. A bridge between LLM agents and physical devices. Import as `dcp`."
 readme = "README.md"
 requires-python = ">=3.11"
 license = { text = "MIT" }