fix: correctly parse turbopuffer distances and compute similarity scores

- fix turbopuffer QueryResponse to match actual API format (direct array,
not wrapped in {rows: ...})
- fix QueryRow to use non-optional dist field as returned by API
- correctly compute similarity scores from cosine distance: 1 - (dist / 2.0)
- remove placeholder score logic that was returning all 1.0s
- fix landing page link to use correct tangled.org URL

search results now show actual semantic similarity scores instead of
placeholder 1.0 values.

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

Co-Authored-By: Claude <[e-mail]>

src/search.rs

···
                 .unwrap_or(&row.id)
                 .to_string();
 
-            // convert cosine distance to similarity score
-            // turbopuffer's dist field contains the cosine distance
-            // for now, use a placeholder score based on rank
-            // TODO: extract actual distance from turbopuffer response
-            let score = 1.0; // placeholder - turbopuffer doesn't return dist in current response
+            // convert cosine distance to similarity score (0-1 range)
+            let score = 1.0 - (row.dist / 2.0);
 
             BufoResult {
                 id: row.id.clone(),

src/turbopuffer.rs

···
 #[derive(Debug, Deserialize, Serialize, Clone)]
 pub struct QueryRow {
     pub id: String,
-    pub dist: Option<f32>,
+    pub dist: f32,
     pub attributes: serde_json::Map<String, serde_json::Value>,
 }
 
···
         }
 
         let body = response.text().await.context("failed to read response body")?;
-        log::debug!("turbopuffer response: {}", body);
+        log::info!("turbopuffer response: {}", body);
 
         serde_json::from_str(&body)
             .context(format!("failed to parse query response: {}", body))

static/index.html

···
     <div class="container">
         <div class="header">
             <h1>find bufo</h1>
-            <p class="subtitle"><a href="https://git.tangled.sh/zzstoatzz.io/find-bufo/src/branch/main/src/search.rs" target="_blank">semantic search</a> for <a href="https://bufo.zone" target="_blank">bufo.zone</a></p>
+            <p class="subtitle"><a href="https://tangled.org/@zzstoatzz.io/find-bufo/blob/main/src/search.rs" target="_blank">semantic search</a> for <a href="https://bufo.zone" target="_blank">bufo.zone</a></p>
         </div>
 
         <div class="search-box">