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Previously `mistral.rs` was the default engine for both safetensors and GGUF models. Now it is only the default for safetensors, `llama.cpp` becomes the default for GGUF.

Why?

- Since #1177 `llama.cpp` is built-in by default, so we can switch.
- `llama.cpp` is very very good at running GGUF (but can't run other types of model), so we should switch.

Dynamo's multi-engine support gives us a secret super-power: we can use the best engine for this specific format or model.

We can still run GGUF with mistralrs by doing `out=mistralrs`.

This change corrects the README.md file in the examples/multimodal folder:
- Correct "vllm worker" to "decode worker"
- Correct assertion that data is moved via NATS when embeddings are moved via RDMA.

Additionally, this change updates the textual graphs with Mermaid graphs for improved presentation on github.com.

- Add Granite to our tokenizer
- Fix pre-processor to load context length correctly
- Add strftime_now Jinja function for prompt templates
- Update llama.cpp
- Handle trtllm errors when not using trtllm

Support depends on the engine:

- `mistral.rs`, our default engine, doesn't support Granite yet.

- `llama.cpp` does and works very well:
```
dynamo-run out=llamacpp ~/llms/granite-3.3-2b-instruct-Q4_K_M.gguf --context-length 16384
```

- `vllm` also works very well:
```
dynamo-run in=http out=vllm ~/llms/granite-3.3-2b-instruct --context-length 16384
```

- `sglang` mostly works, but it doesn't catch the stop token, so we do in the HTTP ingress, and log an error. The Text ingress doesn't catch it because I disabled it to make the raw echo engine work. A bit of work to do here.

Closes: #1245 

Signed-off-by: Hongkuan Zhou <tedzhouhk@gmail.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Co-authored-by: J Wyman <jwyman@nvidia.com>

Changes from default.
- Disable the noisy status messages
- Disable generating docstrings and unit tests

Fixes #286

It was removed from the docs in 0.2.1 and replaced with writing a [standalone Python engine](https://github.com/ai-dynamo/dynamo/blob/main/docs/guides/dynamo_run.md#writing-your-own-engine-in-python).

Also remove the associated `dynamo-run` feature `python`.

Releasing this in 0.3.0 will resolve #784 and #1109.

Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>