chore(release): prepare 1.4.6

[LauraGPT]

Summary

Prepare the FunASR 1.4.6 production hotfix release:

• publish the realtime WebSocket keepalive fix so queued decoding no longer turns delayed pong handling into false connection failures
• include the empty-English-timestamp guard and readable subtitle cue grouping added since 1.4.5
• update all four top-level README release entries and installation links
• pair the Python release with the verified nine-platform llama.cpp v0.2.3 runtime archives
• repair stale current-release tests that still asserted 1.4.1/v0.2.1

Validation

• release, docs, CLI subtitle, timestamp, realtime WebSocket, website-static, and llama.cpp backend regressions: 163 passed
• python -m compileall -q funasr scripts/update_release_runtime_downloads.py
• wheel and sdist built successfully
• twine check: both distributions passed
• wheel metadata: version 1.4.6, knf extra present, no hard torchaudio dependency
• no-dependency wheel install/import: funasr.__version__ == "1.4.6"
• live runtime contract: runtime-llamacpp-v0.2.3, exactly 9 uploaded assets, all 9 SHA-256 digests present
• archive integrity and git diff --check: passed

Publication gate

After merge, publication will run from a fresh worktree at the exact protected main commit on ind-gpu8: rebuild and revalidate wheel + sdist, upload both with the protected PyPI credential, verify PyPI JSON and downloaded artifacts, then push the signed v1.4.6 tag. The tag workflow creates the GitHub Release and attaches the pinned nine llama.cpp runtime archives plus their SHA-256 table.

Signed-off-by: LauraGPT 18321252+LauraGPT@users.noreply.github.com

[LauraGPT]

Publication completed from protected exact main@159f67b154762361d3adf5db6ae2be67a2633c45.

• PyPI: https://pypi.org/project/funasr/1.4.6/
• signed tag v1.4.6 resolves to exact main
• Release workflow: https://github.com/modelscope/FunASR/actions/runs/33226520398 (success)
• GitHub Release: https://github.com/modelscope/FunASR/releases/tag/v1.4.6
• PyPI wheel and sdist were downloaded back, SHA-256 checked, and matched the exact-main build byte for byte
• all 9 copied llama.cpp v0.2.3 assets match the source Release metadata and actual SHA-256; all 9 archives pass integrity checks

The exact-main publication gate reran 163 regressions, source compilation, sdist-to-wheel build, twine check, metadata checks, and a no-dependency install/import smoke test before upload.