feat: comprehensive project improvements

- Fix 14 Clippy warnings across server and bot-sdk
- Add 67 unit tests (32 bot-sdk, 34 server, 1 doctest)
- Add Prometheus metrics endpoint (/api/metrics)
- Add structured JSON logging (EIFELDC_LOG_FORMAT=json)
- Add release workflow (Docker push + GitHub Release + Tauri builds)
- Add rate limiting middleware (EIFELDC_RATE_LIMIT)
- Add CORS restriction (EIFELDC_CORS_ORIGINS)
- Add session token expiry (EIFELDC_SESSION_TTL)
- Add input validation (username/password/homeserver length limits)
- Add upload size limit (EIFELDC_MAX_UPLOAD_MB)
- Upgrade Tauri client from v1 to v2
- Add session store with SQLite persistence
- Add proper error types and cleanup across all crates
- Format all code with cargo fmt
- Update CI pipeline with fmt, clippy, test, frontend, and Tauri checks
- Add README with full API reference and setup guide

client/src-tauri/capabilities/default.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "https://raw.githubusercontent.com/tauri-apps/tauri/dev/crates/tauri-utils/schema.json",
+  "identifier": "default",
+  "description": "Default capability for EifelDC",
+  "windows": ["main"],
+  "permissions": [
+    "core:default",
+    "shell:allow-open",
+    "dialog:allow-open",
+    "dialog:allow-save",
+    "dialog:allow-message",
+    "dialog:allow-ask",
+    "dialog:allow-confirm"
+  ]
+}

client/src-tauri/tauri.conf.json

@@ -1,69 +1,55 @@
 {
-    "build": {
-        "beforeDevCommand": "npm run dev",
-        "beforeBuildCommand": "npm run build",
-        "devPath": "http://localhost:5173",
-        "distDir": "../src-ui/dist"
-    },
-    "package": {
-        "productName": "EifelDC",
-        "version": "0.1.0"
-    },
-    "tauri": {
-        "allowlist": {
-            "all": false,
-            "shell": { "open": true },
-            "dialog": { "all": true },
-            "window": { "all": true }
-        },
-        "bundle": {
-            "active": true,
-            "identifier": "de.eifeldc",
-            "icon": [
-                "icons/32x32.png",
-                "icons/128x128.png",
-                "icons/128x128@2x.png",
-                "icons/icon.icns",
-                "icons/icon.ico"
-            ],
-            "resources": [],
-            "copyright": "",
-            "category": "SocialNetworking",
-            "shortDescription": "EifelDC - Matrix Chat Client",
-            "longDescription": "EifelDC is a Discord-like Matrix chat client built with Tauri, Svelte and Rust.",
-            "windows": {
-                "certificateThumbprint": null,
-                "digestAlgorithm": "sha256",
-                "timestampUrl": ""
-            },
-            "macOS": {
-                "frameworks": [],
-                "minimumSystemVersion": "10.15",
-                "exceptionDomain": "",
-                "signingIdentity": null,
-                "entitlements": "macos/EifelDC.entitlements",
-                "providerShortName": null
-            }
-        },
-        "security": {
-            "csp": "default-src 'self'; connect-src https: wss: http://localhost:*; img-src https: data:; style-src 'self' 'unsafe-inline'; script-src 'self'"
-        },
-        "windows": [
-            {
-                "title": "EifelDC",
-                "width": 1280,
-                "height": 720,
-                "minWidth": 800,
-                "minHeight": 600,
-                "resizable": true,
-                "fullscreen": false,
-                "decorations": true,
-                "transparent": false
-            }
-        ],
-        "systemTray": {
-            "iconPath": "icons/32x32.png",
-            "iconAsTemplate": true
-        }
+  "$schema": "https://raw.githubusercontent.com/tauri-apps/tauri/dev/crates/tauri-cli/schema.json",
+  "productName": "EifelDC",
+  "version": "0.1.0",
+  "identifier": "de.eifeldc",
+  "build": {
+    "beforeDevCommand": "npm run dev",
+    "beforeBuildCommand": "npm run build",
+    "devUrl": "http://localhost:5173",
+    "frontendDist": "../src-ui/dist"
+  },
+  "app": {
+    "windows": [
+      {
+        "title": "EifelDC",
+        "width": 1280,
+        "height": 720,
+        "minWidth": 800,
+        "minHeight": 600,
+        "resizable": true,
+        "fullscreen": false,
+        "decorations": true,
+        "transparent": false
+      }
+    ],
+    "security": {
+      "csp": "default-src 'self'; connect-src https: wss: http://localhost:*; img-src https: data:; style-src 'self' 'unsafe-inline'; script-src 'self'"
     }
+  },
+  "bundle": {
+    "active": true,
+    "icon": [
+      "src-tauri/icons/32x32.png",
+      "src-tauri/icons/128x128.png",
+      "src-tauri/icons/128x128@2x.png",
+      "src-tauri/icons/icon.icns",
+      "src-tauri/icons/icon.ico"
+    ],
+    "category": "SocialNetworking",
+    "shortDescription": "EifelDC - Matrix Chat Client",
+    "longDescription": "EifelDC is a Discord-like Matrix chat client built with Tauri, Svelte and Rust.",
+    "macOS": {
+      "minimumSystemVersion": "10.15",
+      "entitlements": "macos/EifelDC.entitlements"
+    },
+    "windows": {
+      "digestAlgorithm": "sha256"
+    }
+  },
+  "plugins": {
+    "shell": {
+      "open": true
+    }
+  }
 }