feat(sync): complete incremental sync protocol with storage-pull, state management, and tests (#799)

- Add storage-pull strategy: rclone-based sync from remote storage with
  overlay and clean modes, URI parsing (storage://remote:bucket/path),
  transfer parallelism, and automatic rclone availability checking
- Add SyncStateManager: persistent state load/save with configurable
  paths, workspace hash calculation via SHA-256 of key project files,
  and drift detection for external modification awareness
- Add action.yml inputs: syncStrategy, syncInputRef, syncStorageRemote,
  syncRevertAfter, syncStatePath with sensible defaults
- Wire sync into Input (5 getters), BuildParameters (5 fields), index.ts
  (local build path), and RemoteClient (orchestrator path) with post-job
  overlay revert when syncRevertAfter is true
- Add 42 unit tests covering all strategies, URI parsing, state
  management, hash calculation, drift detection, error handling, and
  edge cases (missing rclone, invalid URIs, absent state, empty diffs)
- Add root:true to eslintrc to prevent plugin resolution conflicts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.eslintrc.json

@@ -1,4 +1,5 @@
 {
+  "root": true,
   "plugins": ["jest", "@typescript-eslint", "prettier", "unicorn"],
   "extends": ["plugin:unicorn/recommended", "plugin:github/recommended", "plugin:prettier/recommended"],
   "parser": "@typescript-eslint/parser",