Recover the MCP lane on top of current main

This resolves the stale-branch merge against origin/main, keeps the MCP runtime wiring, and preserves prompt-approved CLI tool execution after the mock parity harness additions landed upstream.

Constraint: Branch had to absorb origin/main changes through a contentful merge before more MCP work
Constraint: Prompt-approved runtime tool execution must continue working with new CLI/mock parity coverage
Rejected: Keep permission enforcer attached inside CliToolExecutor for conversation turns | caused prompt-approved bash parity flow to fail as a tool error
Rejected: Defer the merge and continue on stale history | would leave the lane red against current main
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Runtime permission policy and executor-side permission enforcement are separate layers; do not reapply executor enforcement to conversation turns without revalidating mock parity harness approval flows
Tested: cargo test -p rusty-claude-cli --test mock_parity_harness -- --nocapture; cargo test -p rusty-claude-cli -- --nocapture; cargo test --workspace -- --nocapture
Not-tested: Additional live remote/provider scenarios beyond the existing workspace suite

rust/Cargo.lock

@@ -719,6 +719,15 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "mock-anthropic-service"
+version = "0.1.0"
+dependencies = [
+ "api",
+ "serde_json",
+ "tokio",
+]
+
 [[package]]
 name = "nibble_vec"
 version = "0.1.0"
@@ -1194,6 +1203,7 @@ dependencies = [
  "commands",
  "compat-harness",
  "crossterm",
+ "mock-anthropic-service",
  "plugins",
  "pulldown-cmark",
  "runtime",