fix(dashboard): reorganize F2 Overview and restore hidden controls

[JakeTheRabbit]

Summary

Fixes #33.

• Notifications to the top: the Advisories (notifications) section now leads the Overview page. A compact notification feed dropdown was also added to the header bell icon, so alerts are reachable from every view — not just Overview.
• Sensor info to the top: the Vitals (light/air/leaf/root) section now sits right after notifications instead of being buried mid-scroll.
• Camera up top: room camera, the 3D facility twin, source tank and the live activity feed moved up near the top of Overview, right after the headline card, instead of near the bottom.
• Engine log → its own tab: the log no longer renders above every single view (pushing all content down everywhere). It's now a dedicated "Engine log" tab in the left nav.
• Crop-steering controls restored: the "Control" view (active strategy, arm & pump, relays & solenoids, adaptive steering — the main crop-steering control entities the issue said were missing) already existed in the markup but had no nav entry, making it completely unreachable. Added it to the left nav as "Control".

No markup was deleted — existing blocks were reordered/relabeled and one dangling view was linked into the nav.

Test plan

• Load www/f2.html?demo and confirm Overview shows Advisories → Vitals → headline → zone tiles → camera/3D/tank/activity → irrigation → substrate trend, in that order.
• Click the bell icon in the header from any view and confirm the notification feed dropdown opens/closes correctly.
• Click "Engine log" in the left nav and confirm the log renders full-height in its own tab.
• Click "Control" in the left nav and confirm active strategy / arm & pump / relays / adaptive steering render and write to HA as expected.

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