Fix model.safetensors: restore missing vision tower (was text-only)

## What

`model.safetensors` in this repo was missing the entire vision tower
(all 208 `vision_model.*` tensors):

- **full mirrors**: the file was byte-identical to `text_model.safetensors`
(200 tensors: `text_model.*` + `logit_scale`/`logit_bias`; 1.13 GB) — the
text-only blob had been uploaded under both names. The complete upstream
checkpoint is 1.50 GB / 408 tensors.
- **vision splits**: the file contained only `logit_scale`/`logit_bias`
(144 bytes).

## Impact

Anything loading the repo gets a **silently random-initialized vision tower**
(`from_pretrained` warns about missing keys and continues). Concretely: the
aiWARE `siglip2-chunk` engine bakes this checkpoint into its Docker image at
build time; every image/video embedding it has produced is deterministic but
meaningless noise. Verified empirically: engine-stored vectors vs true SigLIP2
embeddings of the exact same video frames give cosine ~0.06 (receipts:
`services/playground/notebooks/siglip2_vector_verification.ipynb` in the
Veritone agents monorepo).

## Fix

`model.safetensors` replaced with the corresponding content of upstream
`google/siglip2-base-patch16-224` (download sha256-verified against the Hub's LFS metadata;
vision splits: `vision_model.*` + logit scalars extracted from it, matching
the format of the working sibling `-vision` exports — 210 tensors, F32).

## Verification

Structural check of every `*.safetensors` against upstream headers:
`uv run verify_hf_mirror.py Veritone/siglip2-base-patch16-224` (script in the agents monorepo,
`services/playground/scripts/siglip2/`). Collection status when this PR was
prepared: these 4 repos broken, the other 47 in the collection OK.

## Recommended follow-up

Consumers should fail loudly on missing tensors — the engine's Docker bake
step currently prints "weights baked successfully" for a checkpoint that
random-initializes half the model.

model.safetensors

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:325421d6b19e023ba08c05cd3cbd8670c0d1666f2dafe81d1ef2893bff350784
-size 1129238664
+oid sha256:612923381c76ec5a9bed335d1c48827e3f2e506ac31b044b63b2031fadee6a0b
+size 1500800904