Merge feature/smart-backup: partition-aware flash backup and restore

Adds esp_smart_backup and esp_smart_restore tools with chunked reads,
adaptive sizing, skip-empty detection, gzip compression, SHA256
verification, and an esp_backup_plan prompt for pre-flight planning.

Hardened against 11 code review findings including path traversal
protection, atomic manifest writes, and timeout caps.

docs-site/src/content/docs/reference/index.mdx

@@ -103,6 +103,14 @@ All tools follow a consistent pattern: they return a JSON object with a `success
 | `esp_list_tools` | List all tools by category |
 | `esp_health_check` | Environment health check |
 
+### Smart Backup (2 tools + 1 prompt)
+
+| Tool | Description |
+|------|-------------|
+| `esp_smart_backup` | Partition-aware flash backup with chunked reads, skip-empty, and compression |
+| `esp_smart_restore` | Restore a partition-aware backup with SHA256 verification before flashing |
+| `esp_backup_plan` *(prompt)* | Generate an informed backup plan based on device partition layout |
+
 ### Product Catalog (5 tools)
 
 | Tool | Description |

src/mcesptool/components/__init__.py

@@ -15,6 +15,7 @@ from .product_catalog import ProductCatalog
 from .production_tools import ProductionTools
 from .qemu_manager import QemuManager
 from .security_manager import SecurityManager
+from .smart_backup import SmartBackupManager
 
 # Component registry for dynamic loading
 COMPONENT_REGISTRY = {
@@ -28,6 +29,7 @@ COMPONENT_REGISTRY = {
     "diagnostics": Diagnostics,
     "qemu_manager": QemuManager,
     "product_catalog": ProductCatalog,
+    "smart_backup": SmartBackupManager,
 }
 
 __all__ = [
@@ -41,5 +43,6 @@ __all__ = [
     "Diagnostics",
     "QemuManager",
     "ProductCatalog",
+    "SmartBackupManager",
     "COMPONENT_REGISTRY",
 ]

src/mcesptool/server.py

@@ -26,6 +26,7 @@ from .components import (
     ProductionTools,
     QemuManager,
     SecurityManager,
+    SmartBackupManager,
 )
 from .config import ESPToolServerConfig, get_config, set_config
 
@@ -72,6 +73,7 @@ class ESPToolServer:
             self.components["chip_control"] = ChipControl(self.app, self.config)
             self.components["flash_manager"] = FlashManager(self.app, self.config)
             self.components["partition_manager"] = PartitionManager(self.app, self.config)
+            self.components["smart_backup"] = SmartBackupManager(self.app, self.config)
 
             # Advanced features
             self.components["security_manager"] = SecurityManager(self.app, self.config)
@@ -179,6 +181,10 @@ class ESPToolServer:
                     "esp_performance_profile",
                     "esp_diagnostic_report",
                 ],
+                "smart_backup": [
+                    "esp_smart_backup",
+                    "esp_smart_restore",
+                ],
                 "product_catalog": [
                     "esp_product_search",
                     "esp_product_info",