ai: single-switch GPT/Claude backend for the chat cog

Wire the bot's AI chat pipeline (ai_functions.handle_response) to talk to
either OpenAI or the Anthropic Messages API, chosen by one active-config
switch. Behaviour on the default "gpt" config is unchanged.

constants.py:
* guarded `import anthropic` + CLAUDECLIENT (mirrors OPENAICLIENT), netrc
  machine 'anthropic' / ANTHROPIC_API_KEY;
* CLAUDE_LATEST_MODEL / CLAUDE_CHEAP_MODEL (opus-4-8 / haiku-4-5);
* AI_CONFIGS + DEFAULT_AI_CONFIG loaded from an optional 3rd element of
  system_gpt_settings.json (backward compatible - a 2-element file falls
  back to built-in defaults, active "gpt"). Single switch: CONJURER_AI_CONFIG
  env > settings "active" > "gpt".

ai_functions.py:
* provider_generate() dispatches to OpenAI (unchanged openai_call) or the new
  _anthropic_call() (splits system out, alternating messages, max_tokens,
  temperature omitted - Opus 4.8 rejects sampling params);
* AIError normalises both SDKs' exceptions into one category set so
  handle_response keeps its single set of in-character error replies;
* select_model() reads the active config; legacy "gpt-4o" default auto-maps
  to the active provider's model so the switch actually changes the backend;
* set_active_ai_config()/list_ai_configs() with best-effort persistence back
  into system_gpt_settings.json index 2.

ai_commands.py:
* $gadaj_teraz <config> hybrid command (Vykidailo-gated) switches backend at
  runtime;
* graceful guards when OPENAICLIENT is None: personal assistants (OpenAI
  Assistants API) and DALL-E image gen degrade instead of crashing, so a
  Claude-only deployment boots.

system_gpt_settings.json: add the configs block (gpt/claude/_template) as the
collection point for future backends. requirements_bot.txt: add anthropic.
bot.env.example: ANTHROPIC_API_KEY + CONJURER_AI_CONFIG. Unit tests cover the
message splitter, model selection, config listing, and error mapping.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ai_commands.py

@@ -45,6 +45,14 @@ class Events(commands.Cog):
 
     async def cog_load(self):
         self.logger.info("Starting personal assistants")
+        # Personal assistants use the OpenAI Assistants API (threads/runs), which
+        # has no Anthropic equivalent - skip cleanly when OpenAI isn't wired up
+        # (e.g. a Claude-only deployment) instead of crashing the cog load.
+        if OPENAICLIENT is None:
+            self.logger.warning(
+                "OPENAICLIENT niedostępny - osobiści asystenci (OpenAI Assistants API) wyłączeni"
+            )
+            return
         for superfryta_id, superfryta in SPECJALNE_ZIEMNIACZKI.items():
 
             if superfryta[4] != "":
@@ -101,6 +109,40 @@ class Events(commands.Cog):
             else:
                 await ctx.reply("Nope. Nie wiesz jak użyć")
 
+    @commands.hybrid_command(
+        name="gadaj_teraz",
+        description="Przełącz backend AI (np. gpt / claude). Tylko Vykidailo.",
+    )
+    async def gadaj_teraz(self, ctx, nazwa_konfigu: str):
+        async with ctx.channel.typing():
+            is_admin = isinstance(ctx.author, discord.Member) and any(
+                role.name == "Vykidailo" for role in ctx.author.roles
+            )
+            if not is_admin:
+                await discord_friendly_reply(ctx, "Tylko Vykidailo może przełączać AI.")
+                return
+            available = ai_functions.list_ai_configs()
+            if nazwa_konfigu not in available:
+                await discord_friendly_reply(
+                    ctx,
+                    f"Nie znam configu '{nazwa_konfigu}'. Dostępne: {', '.join(available)}",
+                )
+                return
+            try:
+                cfg = ai_functions.set_active_ai_config(nazwa_konfigu)
+            except (KeyError, RuntimeError) as exc:
+                await discord_friendly_reply(
+                    ctx, f"Nie mogę przełączyć na '{nazwa_konfigu}': {exc}"
+                )
+                return
+            self.logger.info(
+                "Przełączono AI na config %s (%s)", nazwa_konfigu, cfg.get("provider")
+            )
+            await discord_friendly_reply(
+                ctx,
+                f"Teraz gadam przez **{nazwa_konfigu}** — {cfg.get('provider')} / {cfg.get('latest_model')}.",
+            )
+
     @commands.hybrid_command(
         name="armia_hammera",
         description="Jeśli nie wiesz jak użyć tej komendy to nawet nie próbuj",
@@ -301,6 +343,15 @@ class Events(commands.Cog):
         if "imaginuje sobie:" in message.content:
             async with channel.typing():
                 self.logger.info("Poczatek procedury obrazkowej")
+                # Image generation is DALL-E (OpenAI); there is no Anthropic
+                # equivalent, so it stays on OpenAI regardless of the chat
+                # backend. Degrade gracefully when OpenAI isn't configured.
+                if OPENAICLIENT is None:
+                    await discord_friendly_reply(
+                        message,
+                        "*Kondziu rozkłada łapska* — malowanie obrazków jest teraz wyłączone (brak OpenAI).",
+                    )
+                    return
                 message_content_lower = message_content_lower.replace("imaginuje sobie: ", "")
                 self.logger.debug("Wywolanie obrazka: %s", message_content_lower)
                 try: