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---

package-lock.json

@@ -1,12 +1,12 @@
 {
-  "name": "@continuous-intelligence/ci",
-  "version": "0.4.0",
+  "name": "@continuous-intelligence/ciagent",
+  "version": "0.5.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "@continuous-intelligence/ci",
-      "version": "0.4.0",
+  "name": "@continuous-intelligence/ciagent",
+      "version": "0.5.0",
       "hasInstallScript": true,
       "license": "MIT",
       "dependencies": {
@@ -14,7 +14,7 @@
         "zod": "^3.23.0"
       },
       "bin": {
-        "ci": "dist/cli/index.js"
+        "ciagent": "dist/cli/index.js"
       },
       "devDependencies": {
         "@types/jest": "^29.5.0",