Fix remaining occurrences of model_name (singular) being used instead
of model_names (list) in main function.

Fixed bug where model_name (singular) was used instead of model_names (list)
in several places, causing UnboundLocalError when running without --model.

- CLI (coder): Add --alias argument to create model aliases
- Config: Add model_aliases dict and resolve_model() method
- Server (coderai): Add server-side alias support with --model-alias
- Aliases are resolved in both client and server when making API calls
- Aliases appear in /v1/models endpoint
- Aliases are persisted in config file

- Add QueueManager class to track waiting requests
- Send 'waiting for model...' frames with time counter at regular intervals
- Send 'Model starting' frame when model begins processing
- Add x_queue_info field to streaming response frames for queue status
- Track queue position and wait time for each client

- Add support for multiple --audio-model arguments (action='append')
- Add support for multiple --image-model arguments (action='append')
- Add 'audio' alias pointing to first audio model
- Add 'vision'/'image' aliases pointing to first image model
- Update MultiModelManager to store audio_models and image_models as lists
- Add audio_model and image_model properties for accessing first model
- Update get_model_for_request to handle aliases
- Update list_models to show all models and aliases
- Fix remaining references in main function to use list-based variables

- Changed --model to -m
- Changed --output to -otxt (output as text)
- Changed --device to -dev
- Changed --file to -f for input audio

The args variable was not accessible in the create_transcription function,
causing a NameError when using --whisper-cpp CLI option. This fix adds
global_args to store the parsed arguments for access in endpoint functions.

- Modified build.sh to build whispercpp with Vulkan support
- Added --audio-vulkan-device argument to specify GPU device for Whisper
- Added Vulkan detection and logging for Whisper transcription
- Set GGML_VULKAN_DEVICE environment variable for GPU selection

faster-whisper doesn't support GGUF format (it's llama.cpp format).
Now detects GGUF files by extension and goes directly to whispercpp.

- Add faster_whisper_failed flag to properly track failures
- When faster-whisper throws non-ImportError (e.g., GGUF not supported),
  now falls back to whispercpp instead of failing
- Applies to both pre-loading and transcription endpoint

- Add specific detection for 'invalid ELF' / 'Mach-O' architecture mismatch errors
- Improve error messages to mention both options:
  - Install PyTorch + faster-whisper
  - Use built-in whispercpp model (tiny/base/small/medium/large)
- Fix critical bug: now raises HTTPException instead of returning None

- Recognize built-in model names: tiny, base, small, medium, large-v1, large
- Allow pre-loading these models directly without file path

- Add better error detection for 'not a valid preconverted model' errors
- Provide clear guidance to users about whispercpp limitations
- Suggest installing faster-whisper with PyTorch or using built-in model names
- Update both transcription endpoint and pre-loading code

- Update transcription endpoint to try faster-whisper first, then whispercpp
- Update pre-loading code to support both backends
- Add whispercpp to all requirements files (vulkan, nvidia, default)
- Remove broken llama.cpp fallback (llama.cpp cannot transcribe Whisper)

When audio model is in GGUF format, use llama.cpp instead of faster-whisper
for pre-loading. This allows using Vulkan backend for audio transcription.

When only one model type is specified (e.g., only --audio-model with no
--model), automatically pre-load it even in on-demand mode. This ensures
the model is downloaded and ready for use.

- Add --loadall flag to pre-load all models at startup
- Add --loadswap flag to keep models in RAM, swap active to VRAM
- Fix bug where load_mode was used before being defined in audio model section
- Remove duplicate load_mode determination code
- Improve error message for no main model specified to include TTS

- Add --tts-model option for Kokoro TTS models
- Add /v1/audio/speech endpoint (OpenAI-compatible)
- Add model caching to prevent redundant downloads
- Replace MD5 with SHA-256 for cache keys
- Move hashlib and pathlib imports to module level

- --model is now optional if using audio or image models only
- Shows helpful error message with examples if no model specified
- Prints available models at startup

- Accept full HTTPS URLs for --model (Vulkan/GGUF models)
- Accept full HTTPS URLs for --audio-model (faster-whisper models)
- Downloads file to temp directory before loading
- Shows download progress percentage