Port feature from vitejs/devtools#527: session-scoped dock UI state across reloads

[antfubot]

Context

vitejs/devtools#527 ("session-scoped dock UI state — restore open/selected dock, tab, and scroll across reloads") by @dvcolomban restored the active ViewJsonRender spec tab + scroll position via sessionStorage, and which dock is open/selected via a new selectedId field folded into the existing localStorage-backed panelStore, so a dev-server restart or HMR full-reload doesn't drop back to the default dock. It touched packages/core/src/client/inject/runtime.ts, webcomponents/components/dock/DockEmbedded.vue, webcomponents/components/views/ViewJsonRender.vue, the json-render Select.ts/Switch.ts/Tabs.ts/TextInput.ts components, json-render/composables/{dock-entry-id,useUncontrolledValue}.ts, and webcomponents/state/{context,docks}.ts in vitejs/devtools, which moved here as part of the v0.9 migration. Equivalents today: packages/hub-ui/src/client/embedded/index.ts, packages/hub-ui/src/client/components/dock/DockEmbedded.vue, packages/hub-ui/src/client/state/{context,docks}.ts for the dock-side pieces, and packages/json-render-ui/src/components/{Select,Switch,Tabs,TextInput}.ts for the json-render pieces (composables likely live alongside them or in a shared packages/json-render-ui/src/ utils area — check current structure).

Original PR description

Why

Reloading the page (dev-server restart, an HMR full-reload, etc.) always dropped back to whatever dock is open by default, which gets annoying mid-debugging.

What changed

• Restores the active spec tab and scroll position inside a ViewJsonRender dock — sessionStorage, keyed per dock and tab, since nothing server-side needs to see these and syncing them across tabs would be unwanted UX.
• Restores which dock is open and selected — selectedId, folded into the existing localStorage-backed panelStore alongside open/mode/position/geometry, rather than a second store, since it's a browser-local singleton exactly like those already are.

Additional context

selectedId living in the same object as open means it inherits #525's shared-state mirror for free, if that one lands — no separate wiring needed there.

Diff: https://github.com/vitejs/devtools/pull/527/files

For agents picking this up

• Read the diff at feat(core): session-scoped dock UI state — restore open/selected dock, tab, and scroll across reloads vitejs/devtools#527 for the sessionStorage-keyed tab/scroll restoration and the panelStore.selectedId addition.
• This PR is explicitly coupled to feat(core): mirror the dock panel's localStorage state into shared state vitejs/devtools#525 (tracked separately as a port here) — land that one first, or coordinate, since selectedId shares panelStore with it.
• Port the dock-state pieces to packages/hub-ui/src/client/embedded/index.ts, components/dock/DockEmbedded.vue, and state/{context,docks}.ts.
• Port the json-render pieces to packages/json-render-ui/src/components/{Select,Switch,Tabs,TextInput}.ts and wherever dock-entry-id/useUncontrolledValue composable equivalents now live — grep the current tree if they've been renamed or consolidated.
• Credit @dvcolomban as the original author: include a Co-authored-by: dvcolomban <...> trailer (look up their GitHub noreply email, or omit if unavailable) and mention them in the PR description.
• Link back to feat(core): session-scoped dock UI state — restore open/selected dock, tab, and scroll across reloads vitejs/devtools#527 in the PR description.
• Close this issue when the port merges.