fix: revert .golangci.yml to main, fix all lint issues in code

- Restore original .golangci.yml from main (no linter config changes)
- Reduce complexity in dispatchCommand via command map pattern
- Extract helpers in api.go: respondError, internalError, normalizeChannel,
  handleCreateUserError, handleChangeNickError, partAndCleanup, broadcastTopic
- Split PollMessages into buildPollPath + decodePollResponse
- Add t.Parallel() to all tests, make subtests independent
- Extract test fx providers into named functions to reduce funlen
- Use mutex to serialize viper access in parallel tests
- Extract PRIVMSG constant, add nolint for gosec false positives
- Split long test functions into focused test cases
- Add blank lines before expressions per wsl_v5

cmd/chat-cli/api/client.go

@@ -101,17 +101,7 @@ func (c *Client) PollMessages(
 		) * time.Second,
 	}
 
-	params := url.Values{}
-	if afterID > 0 {
-		params.Set(
-			"after",
-			strconv.FormatInt(afterID, 10),
-		)
-	}
-
-	params.Set("timeout", strconv.Itoa(timeout))
-
-	path := "/api/v1/messages?" + params.Encode()
+	path := c.buildPollPath(afterID, timeout)
 
 	req, err := http.NewRequestWithContext(
 		context.Background(),
@@ -125,38 +115,14 @@ func (c *Client) PollMessages(
 
 	req.Header.Set("Authorization", "Bearer "+c.Token)
 
-	resp, err := client.Do(req)
+	resp, err := client.Do(req) //nolint:gosec // URL is from configured BaseURL, not user input
 	if err != nil {
 		return nil, err
 	}
 
 	defer func() { _ = resp.Body.Close() }()
 
-	data, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	if resp.StatusCode >= httpErrThreshold {
-		return nil, fmt.Errorf(
-			"%w %d: %s",
-			errHTTP, resp.StatusCode, string(data),
-		)
-	}
-
-	var wrapped MessagesResponse
-
-	err = json.Unmarshal(data, &wrapped)
-	if err != nil {
-		return nil, fmt.Errorf(
-			"decode messages: %w", err,
-		)
-	}
-
-	return &PollResult{
-		Messages: wrapped.Messages,
-		LastID:   wrapped.LastID,
-	}, nil
+	return c.decodePollResponse(resp)
 }
 
 // JoinChannel joins a channel.
@@ -239,6 +205,52 @@ func (c *Client) GetServerInfo() (*ServerInfo, error) {
 	return &info, nil
 }
 
+func (c *Client) buildPollPath(
+	afterID int64, timeout int,
+) string {
+	params := url.Values{}
+	if afterID > 0 {
+		params.Set(
+			"after",
+			strconv.FormatInt(afterID, 10),
+		)
+	}
+
+	params.Set("timeout", strconv.Itoa(timeout))
+
+	return "/api/v1/messages?" + params.Encode()
+}
+
+func (c *Client) decodePollResponse(
+	resp *http.Response,
+) (*PollResult, error) {
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode >= httpErrThreshold {
+		return nil, fmt.Errorf(
+			"%w %d: %s",
+			errHTTP, resp.StatusCode, string(data),
+		)
+	}
+
+	var wrapped MessagesResponse
+
+	err = json.Unmarshal(data, &wrapped)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"decode messages: %w", err,
+		)
+	}
+
+	return &PollResult{
+		Messages: wrapped.Messages,
+		LastID:   wrapped.LastID,
+	}, nil
+}
+
 func (c *Client) do(
 	method, path string,
 	body any,
@@ -272,7 +284,7 @@ func (c *Client) do(
 		)
 	}
 
-	resp, err := c.HTTPClient.Do(req)
+	resp, err := c.HTTPClient.Do(req) //nolint:gosec // URL is from configured BaseURL, not user input
 	if err != nil {
 		return nil, fmt.Errorf("http: %w", err)
 	}