ci: unblock Studio Windows + Linux + Mac smoke (#5741)

Bundles three independent CI regressions hitting the maintainer PR
backlog. Each one is verified end-to-end on a staging fork against
real Ubuntu / macOS / Windows GitHub-hosted runners before this
lands.

1. Windows --no-torch install: pydantic + pydantic-core drift to
   incompatible versions under `uv pip install --no-deps -r
   no-torch-runtime.txt` because pip resolves each independently
   from latest. pydantic.VERSION 2.13.4 pins pydantic-core==2.46.4
   but pydantic-core 2.47.0 was the freshest published wheel, so
   `import pydantic` raised
   `SystemError: pydantic-core 2.47.0 is incompatible with the
   current pydantic version`. Resolve pydantic WITH deps in a
   focused pip call (install.sh, install.ps1,
   install_python_stack.py) before the --no-deps no-torch-runtime
   pass so pip pins pydantic-core to the version pydantic declares.
   pydantic's transitive deps (annotated-types, pydantic-core,
   typing-extensions, typing-inspection) are torch-free. Drop the
   redundant `Patch Studio venv with full typer / pydantic dep
   trees` workaround from the four Windows smoke YAMLs.
   Supersedes #5733 + #5734.

2. Linux Studio Update CI: upstream llama.cpp b9261+ split each
   binary's entry code into a paired `libllama-<binary>-impl.so`
   shared library. `llama-server` and `llama-quantize` NEEDED-link
   against `libllama-server-impl.so` / `libllama-quantize-impl.so`
   with RUNPATH `$ORIGIN`, so the prebuilt overlay must copy those
   alongside the binaries. Without that, ldd reports them missing,
   preflight rejects, the installer falls back to source build, and
   studio-update-smoke annotates `setup.sh idempotency regressed`.
   Add `libllama-*-impl.so*` to the Linux runtime patterns and lock
   the pattern in test_rocm_support.TestRuntimePatterns.

3. Mac Studio UI Chat: change-password submit clicked while
   disabled. The disable gate only checked new + confirm password
   length, but Playwright's first click landed before the
   current-password field's React state had committed, so the form
   was simultaneously logically-invalid (current_password empty) and
   the button was disabled. Tighten the gate to require
   `currentPassword.length >= 8` and mirror the same check in the
   submit handler so Enter / autofill cannot bypass.
   Supersedes #5738.