Close the MCP lifecycle gap from config to runtime tool execution

This wires configured MCP servers into the CLI/runtime path so discovered
MCP tools, resource wrappers, search visibility, shutdown handling, and
best-effort discovery all work together instead of living as isolated
runtime primitives.

Constraint: Keep non-MCP startup flows working without new required config
Constraint: Preserve partial availability when one configured MCP server fails discovery
Rejected: Fail runtime startup on any MCP discovery error | too brittle for mixed healthy/broken server configs
Rejected: Keep MCP support runtime-only without registry wiring | left discovery and invocation unreachable from the CLI tool lane
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Runtime MCP tools are registry-backed but executed through CliToolExecutor state; keep future tool-registry changes aligned with that split
Tested: cargo test -p runtime mcp -- --nocapture; cargo test -p tools -- --nocapture; cargo test -p rusty-claude-cli -- --nocapture; cargo test --workspace -- --nocapture
Not-tested: Live remote MCP transports (http/sse/ws/sdk) remain unsupported in the CLI execution path

rust/crates/rusty-claude-cli/Cargo.toml

@@ -18,6 +18,7 @@ pulldown-cmark = "0.13"
 rustyline = "15"
 runtime = { path = "../runtime" }
 plugins = { path = "../plugins" }
+serde = { version = "1", features = ["derive"] }
 serde_json.workspace = true
 syntect = "5"
 tokio = { version = "1", features = ["rt-multi-thread", "signal", "time"] }