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/core/decision-engine.ts

@@ -1,6 +1,6 @@
 import { execSync } from "node:child_process";
 import { Decision, DecisionCategory, Alternative, confidenceToLevel } from "../types/decisions.js";
-import { CIConfig } from "../types/config.js";
+import { CIAgentConfig } from "../types/config.js";
 import { CommitBuilder, DecisionCommitInput } from "./commit-builder.js";
 import { CommitDecision } from "../types/commit-meta.js";
 
@@ -22,13 +22,13 @@ export interface DecisionResult {
 }
 
 export class DecisionEngine {
-  private config: CIConfig;
+  private config: CIAgentConfig;
   private projectPath: string;
   private currentPhase: number;
   private currentMilestone: string;
   private decisionCounter: number;
 
-  constructor(config: CIConfig, projectPath: string, milestone: string = "v1.0") {
+  constructor(config: CIAgentConfig, projectPath: string, milestone: string = "v1.0") {
     this.config = config;
     this.projectPath = projectPath;
     this.currentPhase = 0;