v1.0.0: Boundary mode with bidirectional LoRa↔TCP transport

Vendor microReticulum library with boundary mode transport fixes:
- Two-whitelist system gates backbone traffic (local addresses +
  mentioned addresses from local devices)
- Allow control_hashes and local destinations through boundary filter
  (fixes backbone→LoRa path discovery)
- Fix get_cached_packet() to call unpack() instead of update_hash()
  (fixes empty destination_hash in path responses)
- LRPROOF Identity::recall null guard
- remaining_hops HEADER_1/BROADCAST fix for final-hop delivery
- PROOF packets excluded from boundary wrapping
- Iterator invalidation fix in transport table cleanup
- is_backbone flag replaces string matching for interface identification

Firmware changes:
- Set is_backbone(true) on backbone TCP interface
- Rename default TcpInterface name to BackboneInterface
- Update comments for dual-use TcpInterface (backbone + local AP)
- Use vendored lib/microReticulum instead of PlatformIO registry

lib/microReticulum/library.json

@@ -0,0 +1,31 @@
+{
+	"name": "microReticulum",
+	"version": "0.2.4",
+	"description": "Port of Reticulum Network Stack to C++ specifically but not exclusively targeting 32-bit and better MCUs",
+	"keywords": "reticulum, rns, mesh, embedded, mcu, esp32, nrf52, native",
+	"repository":
+	{
+		"type": "git",
+		"url": "https://github.com/attermann/microReticulum.git"
+	},
+	"authors":
+	[
+		{
+			"name": "Chad Attermann",
+			"email": "attermann@gmail.com",
+			"maintainer": true
+		}
+	],
+	"license": "Apache-2.0",
+	"homepage": "https://reticulum.network/",
+	"dependencies": {
+		"ArduinoJson": "~7.4.2",
+		"MsgPack": "~0.4.2"
+	},
+	"frameworks": "*",
+	"platforms": "*",
+	"export": {},
+	"exclude": [
+		".github"
+	]
+}