feat(plugin): Fix plugin BoxRef return and Box argument support

- Fixed deadlock in FileBox plugin copyFrom implementation (single lock)
- Added TLV Handle (tag=8) parsing in calls.rs for returned BoxRefs
- Improved plugin loader with config path consistency and detailed logging
- Fixed loader routing for proper Handle type_id/fini_method_id resolution
- Added detailed logging for TLV encoding/decoding in plugin_loader_v2

Test docs/examples/plugin_boxref_return.nyash now works correctly:
- cloneSelf() returns FileBox Handle properly
- copyFrom(Box) accepts plugin Box arguments
- Both FileBox instances close and fini correctly

🤖 Generated with [Claude Code](https://claude.ai/code)

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

docs/development/proposals/nyir/bid_samples/canvas.yaml

@@ -0,0 +1,26 @@
+version: 0
+interfaces:
+  - name: env.canvas
+    box: Canvas
+    methods:
+      - name: fillRect
+        params:
+          - { string: canvas_id }
+          - { i32: x }
+          - { i32: y }
+          - { i32: w }
+          - { i32: h }
+          - { string: color }
+        returns: void
+        effect: io
+
+      - name: fillText
+        params:
+          - { string: canvas_id }
+          - { string: text }
+          - { i32: x }
+          - { i32: y }
+          - { string: font }
+          - { string: color }
+        returns: void
+        effect: io

docs/development/proposals/nyir/bid_samples/console.yaml

@@ -0,0 +1,10 @@
+version: 0
+interfaces:
+  - name: env.console
+    box: Console
+    methods:
+      - name: log
+        params:
+          - { string: msg }
+        returns: void
+        effect: io