Make WebSocket server port configurable

[jb1228]

These changes are primarily to allow multiple instances and keep default behavior at 8928.

Add configurable WebSocket server port (default 8928) across the project and update docs/examples:

• Add DEFAULT_SERVER_PORT and server_port to SendspinClientConfig (include/sendspin/config.h).
• Pass configured server_port into servers via ConnectionManager (src/connection_manager.cpp) and add set_port()/server_port_ members to ESP and host ws_server classes (src/esp/ws_server.{h,cpp}, src/host/ws_server.{h,cpp}).
• Update host server to use server_port_ instead of hardcoded 8928 and log accordingly.
• Update examples (basic_client and tui_client) to accept -p PORT, parse/validate it, set config.server_port, and reflect usage/help text and README notes.
• Add docs entry for server_port in integration-guide.md.

[Copilot]

Pull request overview

Note

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This PR makes the WebSocket server port configurable (instead of hard-coded to 8928) and propagates that configuration through host/ESP server implementations, examples, and docs.

Changes:

• Added SendspinClientConfig::server_port (defaulting to 8928) and a shared DEFAULT_SERVER_PORT constant.
• Updated host and ESP WebSocket servers to use a configurable server_port_ (set via set_port() and wired from ConnectionManager).
• Updated example clients + documentation to expose/describe a -p PORT option and advertise the chosen port via mDNS.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/host/ws_server.h	Adds configurable port storage + setter; updates comments to “configured port”.
src/host/ws_server.cpp	Uses server_port_ when constructing/logging the IXWebSocket server.
src/esp/ws_server.h	Adds configurable port storage + setter; updates capability docs.
src/esp/ws_server.cpp	Uses server_port_ in ESP httpd config.
src/connection_manager.cpp	Plumbs client_->config_.server_port into the WS server via set_port().
include/sendspin/config.h	Introduces DEFAULT_SERVER_PORT and server_port config field.
examples/tui_client/main.cpp	Adds -p parsing and applies it to config + mDNS advertise.
examples/tui_client/README.md	Documents the new -p option.
examples/basic_client/main.cpp	Adds -p parsing and applies it to config + logs + mDNS advertise.
examples/basic_client/README.md	Documents default vs overridden port behavior.
docs/integration-guide.md	Documents server_port in the configuration table.

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