refactor(ui): polish Connectors settings panel

[graydawnc]

Summary

• Flatten each sub-connector card in the detail view from three stacked bordered boxes (Status / Enabled / Sync) into one card with inner dividers — removes the six-box stack that appeared on multi-connector packages like GitHub.
• Demote "Sync now" from a full-width amber-bordered button to an inline text action next to the toggle, aligning with Install/Uninstall and keeping the amber accent rare per DESIGN.md.
• Add a colored status dot (green / amber pulse / red / faint) so state no longer relies on text color alone; add focus ring on the toggle.
• Soften the "auto" label on agent sessions from bright green bold text to the design system's standard small-dot-plus-caps pattern.
• Bump section spacing in the list view from 20px to 24px for clearer rhythm between the three groups.

No logic changes. All state branches (syncing, needs-login, history backfill, error) preserved.

Test plan

• Open Settings → Connectors, verify list view spacing and the softened "auto" label
• Drill into GitHub (multi-connector package); confirm Stars and Notifications each render as a single unified card
• Toggle a connector off/on; confirm status dot + text update and Sync now link appears only when enabled
• Trigger Sync now; confirm pulse animation on dot and "Syncing…" text
• Verify dark mode parity

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