feat: add shareable profile image generation

- Add 1920x1080 HD canvas with trans-pride themed design
- Include profile avatar, name, bio, and lifetime stats
- Show achievement progress with visual progress bar
- Use Tauri fs plugin for cross-platform file reading
- Add scoped file permissions for read/write access

src-tauri/capabilities/default.json

@@ -20,6 +20,14 @@
     "fs:default",
     "fs:allow-read-text-file",
     "fs:allow-write-text-file",
+    {
+      "identifier": "fs:allow-read-file",
+      "allow": [{ "path": "**" }]
+    },
+    {
+      "identifier": "fs:allow-write-file",
+      "allow": [{ "path": "**" }]
+    },
     "core:window:allow-set-size",
     "core:window:allow-set-always-on-top",
     "core:window:allow-inner-size"