Add bash mode for executing shell commands

- Add ! prefix in TUI editor to execute shell commands directly
- Output streams in real-time and is added to LLM context
- Supports multiline commands, cancellation (Escape), truncation
- Preview mode shows last 20 lines, Ctrl+O expands full output
- Commands persist in session history as bashExecution messages
- Add bash command to RPC mode via {type:'bash',command:'...'}
- Add RPC tests for bash command execution and context inclusion
- Update docs: rpc.md, session.md, README.md, CHANGELOG.md

Closes #112

Co-authored-by: Markus Ylisiurunen <markus.ylisiurunen@gmail.com>

packages/coding-agent/test/compaction.test.ts

@@ -193,10 +193,12 @@ describe("createSummaryMessage", () => {
 	it("should create user message with prefix", () => {
 		const msg = createSummaryMessage("This is the summary");
 		expect(msg.role).toBe("user");
-		expect(msg.content).toContain(
-			"The conversation history before this point was compacted into the following summary:",
-		);
-		expect(msg.content).toContain("This is the summary");
+		if (msg.role === "user") {
+			expect(msg.content).toContain(
+				"The conversation history before this point was compacted into the following summary:",
+			);
+			expect(msg.content).toContain("This is the summary");
+		}
 	});
 });