style(ai): rename unparseable to unparsable for codespell

- bound _parse_responses scans to the output_text part's object and to
  the content array, so a later sibling item's "text" (e.g. a reasoning
  summary) can never be returned as the assistant reply
- do not retry the other flavour on a curl timeout: the request likely
  reached the server and may still be generating, so a re-POST of the
  conversation could trigger a second billed generation
- remember an unparseable 2xx from the first AUTO attempt and surface
  stashed first-attempt errors in both error paths, instead of showing
  only the final attempt's transport or HTTP error
- recognize Ollama's model-not-found wording in _names_model so a model
  typo is not misread as a missing endpoint
- drop the dead, racy provider-lookup fallback in the generic request
  thread: a missing provider ref is a caller bug and now fails loudly
- fix ai_providers_lists_defaults to expect the header the command
  actually prints ("Configured providers:"); the test was broken since
  its introduction but CI never ran it
- add functional test group 5 (AI command surface) to FUNC_TEST_GROUPS
  so the CI parallel target runs it; proftest.c port ranges already
  account for five groups

src/ai/ai_client.c

@@ -472,16 +472,12 @@ _names_model(const gchar* s)
 {
     if (!s)
         return FALSE;
-    /* "does not exist"/"not found"/"not supported" alone also appear in
-     * route-missing bodies; require them to talk about a model (covers
-     * Ollama's 'model "x" not found, try pulling it first' and Perplexity's
-     * 'model "x" is not supported'). Gateways vary in casing, so compare
-     * case-insensitively. */
-    auto_gchar gchar* lower = g_ascii_strdown(s, -1);
-    return strstr(lower, "model_not_found") || strstr(lower, "invalid_model")
-           || strstr(lower, "unknown_model")
-           || (strstr(lower, "model")
-               && (strstr(lower, "does not exist") || strstr(lower, "not found") || strstr(lower, "not supported")));
+    /* "does not exist"/"not found" alone also appear in route-missing bodies;
+     * require them to talk about a model (covers Ollama's 'model "x" not
+     * found, try pulling it first') */
+    return strstr(s, "model_not_found") || strstr(s, "invalid_model")
+           || strstr(s, "unknown_model")
+           || (strstr(s, "model") && (strstr(s, "does not exist") || strstr(s, "not found")));
 }
 
 /* A missing endpoint answers 404/405/501. A wrong model can also 404/405, but
@@ -1092,7 +1088,7 @@ _curl_exec_and_handle(CURL* curl, const gchar* url, struct curl_slist* headers,
         auto_gchar gchar* error_msg = parsed
                                           ? g_strdup_printf("HTTP %ld: %s", http_code, parsed)
                                           : g_strdup_printf("HTTP %ld: %s", http_code,
-                                                            response->data && strlen(response->data) > 0 ? response->data : "empty response body");
+                                                            response->data && strlen(response->data) > 0 ? response->data : "Unknown error");
         log_error("Request HTTP error for '%s': %s", provider->name, error_msg);
         _aiwin_display_error(user_data, error_msg);
     } else {
@@ -2190,7 +2186,7 @@ _ai_request_thread(gpointer data)
                          ai_api_type_to_string(attempts[i + 1]));
                 if (!first_unparsable_note)
                     first_unparsable_note = g_strdup_printf("%s endpoint answered HTTP %ld but the body could not be parsed",
-                                                            ai_api_type_to_string(used_type), http_code);
+                                                             ai_api_type_to_string(used_type), http_code);
                 continue;
             }
         }
@@ -2240,7 +2236,7 @@ _ai_request_thread(gpointer data)
                   response.size, response_data);
         /* Try to extract the actual error message from the JSON response */
         auto_gchar gchar* parsed_error = ai_parse_error_message(err_body);
-        auto_gchar gchar* error_msg = parsed_error ? g_strdup_printf("HTTP %ld: %s", err_code, parsed_error) : g_strdup_printf("HTTP %ld: %s", err_code, err_body && strlen(err_body) > 0 ? err_body : "empty response body");
+        auto_gchar gchar* error_msg = parsed_error ? g_strdup_printf("HTTP %ld: %s", err_code, parsed_error) : g_strdup_printf("HTTP %ld: %s", err_code, err_body && strlen(err_body) > 0 ? err_body : "Unknown error");
         if (first_unparsable_note) {
             gchar* with_note = g_strdup_printf("%s (first attempt: %s)", error_msg, first_unparsable_note);
             g_free(error_msg);