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/config.ts

@@ -28,7 +28,8 @@ export type AgentName =
   | "plan-checker"
   | "project-researcher"
   | "research-synthesizer"
-  | "solution-writer";
+  | "solution-writer"
+  | "tester";
 
 export interface AutonomyConfig {
   level: AutonomyLevel;
@@ -71,7 +72,7 @@ export interface ProjectEntry {
   default?: boolean;
 }
 
-export interface CIConfig {
+export interface CIAgentConfig {
   projects: ProjectEntry[];
   active_project: string;
   autonomy: AutonomyConfig;
@@ -83,7 +84,7 @@ export interface CIConfig {
   backend: BackendConfigSection;
 }
 
-export const DEFAULT_CI_CONFIG: CIConfig = {
+export const DEFAULT_CIAGENT_CONFIG: CIAgentConfig = {
   projects: [],
   active_project: "",
   autonomy: {