refactor(rebrand): rename & rebrand CI → CIAgent across all source and test files

- Type renames: CIConfig → CIAgentConfig, DEFAULT_CI_CONFIG → DEFAULT_CIAGENT_CONFIG
- Type renames: CiMetadata → CIAgentMetadata, ParsedCiCommit → ParsedCIAgentCommit
- Function renames: initCI → initCIAgent, isCIInitialized → isCIAgentInitialized
- Function renames: extractCiBlock → extractCIAgentBlock, parseCiBlock → parseCIAgentBlock
- Class renames: CiFiles → CIAgentFiles
- Import paths: ci-files.js → ciagent-files.js
- Directory paths: .ci/ → .ciagent/ across all source and test files
- Check names: ".ci directory exists" → ".ciagent directory exists"
- Check names: "CI config valid" → "CIAgent config valid"
- Temp dir names: ci-*-test- → ciagent-*-test-
- CLI examples: "ci init" → "ciagent init"
- Fix deepMerge infinite recursion bug in config.ts
- ---ci---/---/ci--- block markers preserved unchanged
- All 31 test suites, 370 tests passing

---ci---
phase: 1
milestone: v0.5
plan: 07
task: 07-01-01
status: execute
---/ci---

src/types/pipeline.test.ts

@@ -8,13 +8,14 @@ import {
 } from "../types/pipeline.js";
 
 describe("STAGE_ORDER", () => {
-  it("has 7 stages in correct order", () => {
+  it("has 8 stages in correct order", () => {
     expect(STAGE_ORDER).toEqual([
       "specify",
       "clarify",
       "research",
       "plan",
       "execute",
+      "test",
       "verify",
       "complete",
     ]);
@@ -27,7 +28,8 @@ describe("getNextStage", () => {
     expect(getNextStage("clarify")).toBe("research");
     expect(getNextStage("research")).toBe("plan");
     expect(getNextStage("plan")).toBe("execute");
-    expect(getNextStage("execute")).toBe("verify");
+    expect(getNextStage("execute")).toBe("test");
+    expect(getNextStage("test")).toBe("verify");
     expect(getNextStage("verify")).toBe("complete");
   });
 
@@ -51,6 +53,7 @@ describe("createInitialPipelineState", () => {
     expect(state.research_completed).toBe(false);
     expect(state.plan_completed).toBe(false);
     expect(state.execute_completed).toBe(false);
+    expect(state.test_completed).toBe(false);
     expect(state.verify_completed).toBe(false);
     expect(state.errors).toHaveLength(0);
     expect(state.started_at).toBeTruthy();