studio/tests: make Playwright model-selector probe best-effort (#5371)

* studio/tests: make Playwright model-selector probe best-effort

The Mac Studio UI CI run 25664825320 / job 75334476211 failed at
playwright_chat_ui.py:483 with:

    playwright._impl._errors.TimeoutError:
      Locator.text_content: Timeout 60000ms exceeded.

Timeline from that job's log:
    11:40:51  [ui] OK default_models[0] = unsloth/gemma-4-E2B-it-GGUF
    11:41:51  TimeoutError (exactly 60 s later)

Root cause: count() and text_content() are two independent queries
against the live DOM. The chat surface re-mounts the model selector
while /api/models/list resolves the default-model badge, so the
button matches the OR-selector at count() time but is briefly
detached when text_content() re-queries. The page-wide default
action timeout was bumped to 60 s on line 177, so the informational
probe blocked for a full minute and then hard-failed.

The block is clearly best-effort: it is gated on if count() > 0 and
the only side effects are info(...) and shoot(...). Replace the
count-then-text dance with a single text_content(timeout=2_000)
inside a try/except, matching the pattern the rest of this file
already uses for networkidle, screenshot capture, and composer
wait. Happy path still prints the button text and snaps
03b-default-model-button; a miss now logs WARN and continues to the
/api/inference/load step.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/studio/playwright_chat_ui.py

@@ -479,8 +479,16 @@ with sync_playwright() as p:
         'button:has-text("Qwen"), '
         'button:has-text("Llama")'
     ).first
-    if selector_btn.count() > 0:
-        sel_text = (selector_btn.text_content() or "").strip()
+    # Best-effort: the selector re-mounts as /api/models/list resolves,
+    # so use a short timeout and skip the snapshot on miss.
+    sel_text = ""
+    try:
+        sel_text = (selector_btn.text_content(timeout = 2_000) or "").strip()
+    except Exception as _sel_err:
+        info(
+            f"WARN: model-selector probe skipped: {type(_sel_err).__name__}: {_sel_err}"
+        )
+    if sel_text:
         info(f"model selector button text: {sel_text!r}")
         shoot("03b-default-model-button")