feat(ai): improve runtime capability reporting and context settings

Add explicit chat capability tracking, expose formatted runtime capabilities
in the info command, and support a max context size option for user AI settings.

Also update Ollama base URL resolution to use OLLAMA_ADDRESS and simplify
provider chat command execution.

src/callback_commands/user-settings.ts

@@ -71,7 +71,7 @@ export class UserSettingsCallback extends CallbackCommand {
 
         if (parsed.screen === "contextSize" && parsed.contextSizeChoice) {
             const choice = normalizeAiContextSizeChoice(parsed.contextSizeChoice);
-            if (choice) {
+            if (choice || choice === -1) {
                 const result = await setUserAiContextSizeChoice(query.from.id, choice);
                 settings = result.settings;
             }