fix: pull ollama embedding model if necessary (#1209)

Embedding models are tiny and can be pulled on-demand. Let's do that so
the user doesn't have to do "yet another thing" to get themselves set
up.

Thanks @hardikjshah for the suggestion.

Also fixed a build dependency miss (TODO: distro_codegen needs to
actually check that the build template contains all providers mentioned
for the run.yaml file)

## Test Plan 

First run `ollama rm all-minilm:latest`. 

Run `llama stack build --template ollama && llama stack run ollama --env
INFERENCE_MODEL=llama3.2:3b-instruct-fp16`. See that it outputs a
"Pulling embedding model `all-minilm:latest`" output and the stack
starts up correctly. Verify that `ollama list` shows the model is
correctly downloaded.

llama_stack/templates/ollama/build.yaml

@@ -6,6 +6,7 @@ distribution_spec:
     - remote::ollama
     vector_io:
     - inline::faiss
+    - inline::sqlite_vec
     - remote::chromadb
     - remote::pgvector
     safety:

llama_stack/templates/ollama/ollama.py

@@ -25,7 +25,7 @@ from llama_stack.templates.template import DistributionTemplate, RunConfigSettin
 def get_distribution_template() -> DistributionTemplate:
     providers = {
         "inference": ["remote::ollama"],
-        "vector_io": ["inline::faiss", "remote::chromadb", "remote::pgvector"],
+        "vector_io": ["inline::faiss", "inline::sqlite_vec", "remote::chromadb", "remote::pgvector"],
         "safety": ["inline::llama-guard"],
         "agents": ["inline::meta-reference"],
         "telemetry": ["inline::meta-reference"],