feat(phase9): implement WebSocket transport and failover system

Implements Phase 9: Remoting / Cloud Hybrid Deployment with complete
WebSocket transport support and comprehensive failover mechanisms.

**WebSocket Transport (remote_client.rs):**
- Added WebSocket support to RemoteMcpClient using tokio-tungstenite
- Full bidirectional JSON-RPC communication over WebSocket
- Connection establishment with error handling
- Text/binary message support with proper encoding
- Connection closure detection and error reporting

**Failover & Redundancy (failover.rs - 323 lines):**
- ServerHealth tracking: Healthy, Degraded, Down states
- ServerEntry with priority-based selection (lower = higher priority)
- FailoverMcpClient implementing McpClient trait
- Automatic retry with exponential backoff
- Circuit breaker pattern (5 consecutive failures triggers Down state)
- Background health checking with configurable intervals
- Graceful failover through server priority list

**Configuration:**
- FailoverConfig with tunable parameters:
  - max_retries: 3 (default)
  - base_retry_delay: 100ms with exponential backoff
  - health_check_interval: 30s
  - circuit_breaker_threshold: 5 failures

**Testing (phase9_remoting.rs - 9 tests, all passing):**
- Priority-based server selection
- Automatic failover to backup servers
- Retry mechanism with exponential backoff
- Health status tracking and transitions
- Background health checking
- Circuit breaker behavior
- Error handling for edge cases

**Dependencies:**
- tokio-tungstenite 0.21
- tungstenite 0.21

All tests pass successfully. Phase 9 specification fully implemented.

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

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

crates/owlen-core/src/tools/web_scrape.rs

@@ -0,0 +1,102 @@
+use super::{Tool, ToolResult};
+use crate::Result;
+use anyhow::Context;
+use async_trait::async_trait;
+use serde_json::{json, Value};
+
+/// Tool that fetches the raw HTML content for a list of URLs.
+///
+/// Input schema expects:
+///   urls: array of strings (max 5 URLs)
+///   timeout_secs: optional integer per‑request timeout (default 10)
+pub struct WebScrapeTool {
+    // No special dependencies; uses reqwest_011 for compatibility with existing web_search.
+    client: reqwest_011::Client,
+}
+
+impl Default for WebScrapeTool {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl WebScrapeTool {
+    pub fn new() -> Self {
+        let client = reqwest_011::Client::builder()
+            .user_agent("OwlenWebScrape/0.1")
+            .build()
+            .expect("Failed to build reqwest client");
+        Self { client }
+    }
+}
+
+#[async_trait]
+impl Tool for WebScrapeTool {
+    fn name(&self) -> &'static str {
+        "web_scrape"
+    }
+
+    fn description(&self) -> &'static str {
+        "Fetch raw HTML content for a list of URLs"
+    }
+
+    fn schema(&self) -> Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "urls": {
+                    "type": "array",
+                    "items": { "type": "string", "format": "uri" },
+                    "minItems": 1,
+                    "maxItems": 5,
+                    "description": "List of URLs to scrape"
+                },
+                "timeout_secs": {
+                    "type": "integer",
+                    "minimum": 1,
+                    "maximum": 30,
+                    "default": 10,
+                    "description": "Per‑request timeout in seconds"
+                }
+            },
+            "required": ["urls"],
+            "additionalProperties": false
+        })
+    }
+
+    fn requires_network(&self) -> bool {
+        true
+    }
+
+    async fn execute(&self, args: Value) -> Result<ToolResult> {
+        let urls = args
+            .get("urls")
+            .and_then(|v| v.as_array())
+            .context("Missing 'urls' array")?;
+        let timeout_secs = args
+            .get("timeout_secs")
+            .and_then(|v| v.as_u64())
+            .unwrap_or(10);
+
+        let mut results = Vec::new();
+        for url_val in urls {
+            let url = url_val.as_str().unwrap_or("");
+            let resp = self
+                .client
+                .get(url)
+                .timeout(std::time::Duration::from_secs(timeout_secs))
+                .send()
+                .await;
+            match resp {
+                Ok(r) => {
+                    let text = r.text().await.unwrap_or_default();
+                    results.push(json!({ "url": url, "content": text }));
+                }
+                Err(e) => {
+                    results.push(json!({ "url": url, "error": e.to_string() }));
+                }
+            }
+        }
+        Ok(ToolResult::success(json!({ "pages": results })))
+    }
+}