Add ROS 2 parameter viewing and setting

[rosterloh]

Summary

Adds end-to-end support for viewing and setting ROS 2 parameters on any node in the graph, reached through the standard rcl_interfaces parameter services.

• Protocol (talos-common) — ParamValue/ParamInfo types with text inference and round-trip-safe Display; ListParameters/GetParameters/SetParameter requests and Parameters/ParameterSet responses.
• Agent (talos-agent) — Acts as a parameter service client: per request it creates short-lived clients to the target node's list_parameters/get_parameters/set_parameters services (serviced by the bridge's spinning executor), with bounded service-availability and call timeouts. ListParameters lists then fetches values in one round trip. Value conversions both directions.
• CLI (talos-cli) — list-params <node>, get-param <node> <names…>, set-param <node> <name> <value> (value type inferred; non-zero exit on rejection).
• TUI (talos-tui) — New Params tab (5): node list → Enter loads params → e edits a value in place → Enter applies and auto-refreshes.
• Docs (protocol/CLI/TUI pages + new features/parameters.md) and CHANGELOG.md updated.

Verification

The ROS-dependent crate can't be built without a ROS 2 environment, so:

• Protocol — the real source was compiled standalone with serde+bincode; new round-trip + parse/Display tests pass (45 talos-common tests green overall, including the QUIC/UDS session tests that confirm new response variants pass through).
• CLI + TUI — compiled in a clean workspace; no clippy warnings in new code.
• Agent — the parameter handlers and conversions were compiled verbatim against a faithful stub of the exact rclrs 0.7 + rcl_interfaces API surface (field names, create_client/call/notify_on_service_ready signatures, the generic call_service, and Send-ness of the spawned handler futures). Added integration tests for the no-graph error path.

Note: parameter access targets other nodes' standard parameter services (like ros2 param), so the target node must be running; otherwise the agent returns a bounded-timeout error rather than hanging.