ci: use vLLM 0.29 release image and align installation docs

Drop the old-base wheel reinstall and dependency repair block. Update source installation and configuration references to vLLM 0.29 while retaining explicitly matched 0.28 prebuilt Omni examples until its next release.

Validation: official image and CUDA/ROCm release artifacts checked; 6 documentation tests passed; diff whitespace checks passed. Markdown lint reports existing snippet/anchor issues. Container build not run: no builder available.
Signed-off-by: tzhouam <tzhouam@connect.ust.hk>

docs/getting_started/installation/gpu.md

@@ -34,6 +34,8 @@ vLLM-Omni is a Python library that supports the following GPU variants. The libr
 
 ### Pre-built wheels
 
+The source-install instructions target vLLM 0.29.0. Until vLLM-Omni 0.29.0 artifacts are published, the CUDA/ROCm pre-built examples below remain on the matching 0.28.0 release pair.
+
 Note: Pre-built wheels are currently available for vLLM-Omni 0.11.0rc1, 0.12.0rc1, 0.14.0rc1, 0.14.0, 0.16.0, 0.18.0, 0.20.0, 0.21.0, 0.22.0, 0.23.0, 0.24.0, 0.25.0, 0.26.0, and 0.28.0. If you need a newer unreleased revision, please [build from source](https://docs.vllm.ai/projects/vllm-omni/en/latest/getting_started/installation/gpu/#build-wheel-from-source).
 
 === "NVIDIA CUDA"