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/verification/index.test.ts

@@ -7,8 +7,8 @@ describe("VerificationPipeline", () => {
   let tempDir: string;
 
   beforeEach(() => {
-    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "ci-pipeline-test-"));
-    const ciDir = path.join(tempDir, ".ci");
+    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "ciagent-pipeline-test-"));
+    const ciDir = path.join(tempDir, ".ciagent");
     fs.mkdirSync(ciDir, { recursive: true });
     fs.writeFileSync(path.join(ciDir, "config.json"), JSON.stringify({ autonomy: { level: "full" } }));
     fs.writeFileSync(path.join(ciDir, "specification.md"), "# Test\n## Objective\nBuild it\n\n## Requirements\n- Feature A\n");