[Refactor/Chore] Limit initial translation payloads to required namespaces

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Description

Load translation namespaces according to shell/route needs instead of serializing every namespace through the root layout.

web/i18n-config/server.ts:getResources loads every namespacesInFileName entry with Promise.all. web/app/components/provider/i18n-server.tsx passes that complete resource object to the client provider, mounted by the root layout.

The current registry has 38 namespaces. Compact locale JSON measurements before RSC serialization overhead:

Locale	Bytes	Estimated gzip bytes
en-US	408,225	105,639
zh-Hans	392,775	111,105

A DOM-backed inspection of the local datasets page found a 435,637-character inline script containing appDebug, knowledgeSpace, workflow, and billing keys together. That script also contains other data; its entire size is not attributable to translations. These resources travel in HTML/RSC data, so inspecting only package JS size misses the cost.

Motivation

Initial page data includes translations for unrelated features. Define initial shell/route namespace requirements, then load additional namespaces when needed.

Acceptance criteria:

• Reduce initial translation resources on representative routes, including a lightweight route and datasets.
• Update client initialization together with server selection: getInitOptions currently sets ns: namespaces, so dropping server resources alone could trigger immediate requests for all missing namespaces.
• Preserve server/client text consistency, fallback locale behavior, language switching, and feature navigation.
• Compare production HTML/RSC transfer and subsequent translation requests, including request waterfalls; do not merely move the same cost to dozens of immediate requests.

Additional Context

Observed on a local Dify 1.17.1 development branch based on 06e473015a9a1abb71da88ac0a0e92d96a992008, with local DevTools integration patches; Vinext 1.0.0-beta.10, Vite+ core 0.3.2, Node 24.21.0. Recheck against current main before implementation. Build measurements are diagnostic baselines, not controlled production network benchmarks.