SvelteKit block explorer with real RPC integration (#110)

* Initial plan

* Add block explorer API endpoints and UI

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

* Add block explorer documentation and finalize implementation

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

* Fix SearchResult enum serialization for proper JavaScript interop

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

* Refactor to SvelteKit-based explorer with real RPC calls

- Remove mock data API endpoints from bitcell-admin
- Remove inline HTML/JS explorer
- Create new SvelteKit application in crates/bitcell-explorer/
- Connect to real BitCell node RPC endpoints
- No SSR, client-side only SPA
- Proper input validation and XSS protection
- Accessibility improvements (ARIA labels, keyboard nav)
- Updated documentation

Addresses code review comments:
- Removed all mock/dummy data
- Added hex validation for addresses and hashes
- Fixed XSS vulnerabilities
- Added proper accessibility features
- Using modern web framework (Svelte, not React)

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

Author: Copilot

crates/bitcell-explorer/.gitignore

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+# Dependencies
+node_modules/
+
+# Build output
+/build
+/.svelte-kit
+/package
+
+# Environment
+.env
+.env.local
+.env.*.local
+
+# Editor
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*

crates/bitcell-explorer/README.md

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+# BitCell Block Explorer
+
+A SvelteKit-based block explorer for the BitCell blockchain.
+
+## Features
+
+- Real-time block viewing
+- Transaction search and details
+- Account balance and transaction history
+- Tournament battle visualization
+- Trust score display (EBSL)
+- Universal search (block height, hash, tx hash, address)
+
+## Development
+
+```bash
+# Install dependencies
+npm install
+
+# Run development server
+npm run dev
+
+# Build for production
+npm run build
+```
+
+## Configuration
+
+The explorer connects to a BitCell node RPC endpoint. By default, it expects the node to be running on `localhost:9545`.
+
+To change the RPC endpoint, edit `vite.config.js`:
+
+```javascript
+server: {
+  proxy: {
+    '/rpc': {
+      target: 'http://your-node:port',
+      changeOrigin: true
+    }
+  }
+}
+```
+
+## Architecture
+
+- **No SSR**: This is a client-side only application (SPA)
+- **Real RPC calls**: All data comes from the BitCell node via JSON-RPC
+- **No mock data**: Every piece of information is fetched from the live blockchain
+
+## API Integration
+
+The explorer uses these RPC methods:
+
+- `eth_blockNumber` - Get current block height
+- `eth_getBlockByNumber` - Get block details
+- `eth_getTransactionByHash` - Get transaction details
+- `eth_getBalance` - Get account balance
+- `eth_getTransactionCount` - Get account nonce
+- `bitcell_getNodeInfo` - Get node information
+- `bitcell_getTournamentState` - Get tournament state
+- `bitcell_getBattleReplay` - Get battle replay data
+- `bitcell_getMinerStats` - Get miner statistics
+
+## Security
+
+- All user input is validated and sanitized
+- XSS protection through proper escaping
+- ARIA labels for accessibility
+- Keyboard navigation support

crates/bitcell-explorer/package.json

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+{
+  "name": "bitcell-explorer",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "vite dev",
+    "build": "vite build",
+    "preview": "vite preview",
+    "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
+    "check:watch": "svelte-kit sync && svelte-check --tsconfig ./jsconfig.json --watch"
+  },
+  "devDependencies": {
+    "@sveltejs/adapter-static": "^3.0.1",
+    "@sveltejs/kit": "^2.0.0",
+    "@sveltejs/vite-plugin-svelte": "^3.0.0",
+    "svelte": "^4.2.7",
+    "svelte-check": "^3.6.0",
+    "typescript": "^5.0.0",
+    "vite": "^5.0.3"
+  },
+  "type": "module"
+}