feat: initial implementation of content-addressed incremental backup engine

Rust-centric architecture with TypeScript facade following smartproxy/smartstorage pattern.
Core engine in Rust (FastCDC chunking, SHA-256, gzip, AES-256-GCM + Argon2id, binary pack files,
global index, snapshots, locking, verification, pruning, repair). TypeScript provides npm interface
via @push.rocks/smartrust RustBridge IPC with Unix socket streaming for ingest/restore.
All 14 integration tests pass.

npmextra.json

@@ -0,0 +1,40 @@
+{
+  "@git.zone/cli": {
+    "projectType": "npm",
+    "module": {
+      "githost": "code.foss.global",
+      "gitscope": "push.rocks",
+      "gitrepo": "containerarchive",
+      "description": "content-addressed incremental backup engine with deduplication, encryption, and error correction",
+      "npmPackagename": "@push.rocks/containerarchive",
+      "license": "MIT",
+      "keywords": [
+        "backup",
+        "deduplication",
+        "content-addressed",
+        "incremental",
+        "archive",
+        "encryption",
+        "chunking",
+        "fastcdc",
+        "pack-files"
+      ]
+    },
+    "release": {
+      "registries": [
+        "https://verdaccio.lossless.digital",
+        "https://registry.npmjs.org"
+      ],
+      "accessLevel": "public"
+    }
+  },
+  "@git.zone/tsrust": {
+    "targets": [
+      "linux_amd64",
+      "linux_arm64"
+    ]
+  },
+  "@git.zone/tsdoc": {
+    "legal": "\n## License and Legal Information\n\nThis module is part of the @push.rocks ecosystem, maintained by Task Venture Capital GmbH.\n\nLicensed under MIT. See LICENSE file for details.\n\nFor questions or commercial licensing, contact: hello@task.vc\n"
+  }
+}