feat: per-instance reload + manual hibernate/wake from sidebar context menu

[Teamingzooper]

Summary

Right-click any sidebar instance now exposes actions that operate on that instance rather than the active one. Pairs nicely with #10 (auto-hibernate) — once you have hibernation on, you can manually trigger it for a specific instance instead of waiting for the timer.

Branch base: `feat/sidebar-search` — seventh in the stack. Merge order: #6 → #7 → #8 → #9 → #10 → #11 → this.

What changes in the context menu

Item	Before	After
Reload	Activated then reloaded the instance (jumped you to it)	Reloads in place — no activation. Useful for refreshing a background tab.
Hibernate now	n/a	New. Appears below Mute when the hibernate feature is enabled AND the instance is not currently active. Frees its memory immediately.
Wake	n/a	New. Appears in place of Hibernate when the instance is asleep. Recreates the view in the background without jumping to it.

Architecture

Three new `ViewService` methods, all idempotent and safe-on-unknown-id:

• `reloadInstance(id)` — `ensure()`s the view (waking if hibernated) then `webContents.reload()`.
• `hibernateInstance(id)` — same teardown path as the periodic sweep, but triggered manually. Skipped if the instance is the active one or has no live view.
• `wakeInstance(id)` — rebuilds a hibernated view in the background, without activating it.

Three matching IPC channels (`nexus:instances:reload`, `nexus:instances:hibernate`, `nexus:instances:wake`), Zod-validated input.

Renderer store gets matching actions with optimistic updates of the `hibernatedInstances` slice so the 💤 indicator flicks on/off immediately.

Test plan

• `npm run typecheck` — clean
• `npm run test` — 178/178 passing
• `npm run build` — renderer + main both clean
• Manual smoke: right-click a background instance, hit Reload. The instance reloads its page but you stay on whatever's active.
• Manual smoke (after feat: auto-hibernate inactive instances to reclaim memory #10 is merged): enable hibernation in Settings → Performance. Right-click a background instance → "Hibernate now". The 💤 appears. Right-click again → "Wake". The 💤 clears and the view rebuilds.
• Manual smoke: right-click the currently-active instance with hibernate on — should NOT show "Hibernate now" (active is never hibernated).

🤖 Generated with Claude Code