insight-chat: ToolGateOpts + per-tool description rewrites

Tools whose backing tables are empty (calendar, location_history,
daily_summaries) drop out of the catalog so the LLM doesn't waste
iteration budget calling them only to receive "no results found".
Vision and apollo gates already existed; this generalizes the pattern.

search_messages gains start_ts/end_ts/contact_id filters (date filter
is a client-side post-filter; SMS-API only accepts contact_id natively
on the search endpoint).

Descriptions follow a consistent convention: one sentence (what +
when), param semantics, examples for tools with non-obvious param
choices. No more all-caps headers, no more identity-prescriptive
language inside descriptions.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ai/sms_client.rs

@@ -295,6 +295,47 @@ impl SmsApiClient {
         Ok(data.results)
     }
 
+    /// Same shape as `search_messages` but with optional `contact_id`. The
+    /// SMS-API endpoint accepts contact_id natively; date filtering is the
+    /// caller's responsibility (post-filter on the returned rows).
+    pub async fn search_messages_with_contact(
+        &self,
+        query: &str,
+        mode: &str,
+        limit: usize,
+        contact_id: Option<i64>,
+    ) -> Result<Vec<SmsSearchHit>> {
+        let mut url = format!(
+            "{}/api/messages/search/?q={}&mode={}&limit={}",
+            self.base_url,
+            urlencoding::encode(query),
+            urlencoding::encode(mode),
+            limit
+        );
+        if let Some(cid) = contact_id {
+            url.push_str(&format!("&contact_id={}", cid));
+        }
+
+        let mut request = self.client.get(&url);
+        if let Some(token) = &self.token {
+            request = request.header("Authorization", format!("Bearer {}", token));
+        }
+
+        let response = request.send().await?;
+        if !response.status().is_success() {
+            let status = response.status();
+            let body = response.text().await.unwrap_or_default();
+            return Err(anyhow::anyhow!(
+                "SMS search request failed: {} - {}",
+                status,
+                body
+            ));
+        }
+
+        let data: SmsSearchResponse = response.json().await?;
+        Ok(data.results)
+    }
+
     pub async fn summarize_context(
         &self,
         messages: &[SmsMessage],