fix: URL-encode query params in client and pass --meta to server on save

- URL-encode all query parameter keys and values in get_json_with_query
  and post_stream. Previously raw JSON like {"project":"alpha"} was
  sent unencoded, causing 'invalid uri character' errors.
- Pass settings.meta (key=value pairs) from client save to server as
  metadata. Previously always passed empty HashMap, so --meta was
  silently ignored in client save mode.

src/client.rs

@@ -15,6 +15,24 @@ pub struct ItemInfo {
     pub metadata: HashMap<String, String>,
 }
 
+/// Percent-encode a value for use in a URL query string.
+fn url_encode(s: &str) -> String {
+    let mut result = String::with_capacity(s.len() * 3);
+    for byte in s.bytes() {
+        match byte {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                result.push(byte as char);
+            }
+            _ => {
+                result.push('%');
+                result.push(char::from_digit((byte >> 4) as u32, 16).unwrap());
+                result.push(char::from_digit((byte & 0xF) as u32, 16).unwrap());
+            }
+        }
+    }
+    result
+}
+
 pub struct KeepClient {
     base_url: String,
     agent: ureq::Agent,
@@ -113,7 +131,7 @@ impl KeepClient {
                 if i > 0 {
                     url.push('&');
                 }
-                url.push_str(&format!("{key}={value}"));
+                url.push_str(&format!("{}={}", url_encode(key), url_encode(value)));
             }
         }
         let mut req = self.agent.get(&url);
@@ -166,7 +184,7 @@ impl KeepClient {
                 if i > 0 {
                     url.push('&');
                 }
-                url.push_str(&format!("{key}={value}"));
+                url.push_str(&format!("{}={}", url_encode(key), url_encode(value)));
             }
         }