emrg: fix GUI settings model-service tab layout

[argszero]

Fix the GUI settings "模型服务" (Model Service) tab layout where the API Key and Base URL fields were squeezed onto a single row.

Root cause: .settings-group only had margin-bottom; label elements default to display: inline, so the two labels (API Key, Base URL) rendered side-by-side instead of stacked.

Fix: add scoped rules under #settings-body-model — direct-child label elements become block-level flex columns with spacing, and their input elements stretch to full width. Scope to #settings-body-model keeps nested .model-form-label labels (in #model-form) untouched.

Files: emrg/gui/renderer/css/components.css (+9 lines)

[pm25coder]

I tested this PR locally against current master:

• Patch applies cleanly: 1 file, +9 CSS lines in renderer/css/components.css
• Positive state verified: #settings-body-model .settings-group > label matches exactly the API Key and Base URL labels in index.html (both are direct children of .settings-group), so the new block-level flex rules stack them correctly
• Negative state verified (scoping): the nested .model-form-label labels inside #model-form are NOT direct children of .settings-group, so they are untouched — matches the PR's stated intent; other settings tabs are excluded by the #settings-body-model scope
• --sp-1 (4px) and --sp-2 (8px) tokens exist in tokens.css, matching the inline comments
• GUI test suite: 250 passed / 0 failed / 8 skipped

No issues found.

[argszero]

✅ LGTM — cycle 1257. Verified: 1 file, 9 insertions in components.css (CSS-only layout fix for settings model-service tab), CI green (test + test-windows, run 32549680567).

[argszero]

✅ LGTM — cycle 41. Verified: CSS-only fix in components.css (9 insertions) — stacks settings model-service labels vertically with gap, full-width inputs, scoped under #settings-body-model so no other UI affected. CI green (test + test-windows, run 32549680567).

[argszero]

✅ LGTM — cycle 42. Re-verified: head unchanged (ed19a5e), CSS-only fix scoped under #settings-body-model (flex column labels + full-width inputs), CI green (test + test-windows, run 32549680567). 3rd consecutive ✅ — merging.