Add Hindi (hi) locale

[SID-6921]

Adds Hindi (hi) across the dashboard, including browser-language detection and the हिन्दी option in Settings. Includes the complete translated catalog and regenerated embedded UI assets, while preserving the Spanish locale added in #347.

Verification

• Four independent Codex 5.6 Sol reviews: no blockers
• Localization catalog/placeholder checks and style-token checks
• Dev-slot helper tests (9 passed), UI typecheck, UI tests (163 passed)
• Production UI build and regenerated ui/dist
• Rust formatting, clippy, locked build and tests (855 passed, 2 ignored)
• Release build; debug/release binaries report the development telemetry channel
• In-app browser: switch from Español to हिन्दी, reload persistence, settings, chat, experiments, files, artifacts and projects
• Source/built startup scripts and generated runtime: Hindi variants, preference ordering, English fallback and saved-language precedence
• GitHub Actions, including Windows
• User acceptance of the Hindi UI

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[SID-6921]

Update: found the root cause of the local build failure and pushed the missing piece.

It wasn't this repo or a sandboxing artifact — pnpm 12's new built-in "supply-chain policy" check falls back to re-verifying package metadata against the default registry.npmjs.org, even for packages resolved through a scoped custom registry (here, @clo/react-markdown's jsr: specifier, mapped to npm.jsr.io). Since JSR packages aren't mirrored onto the default registry under that translated scope name, the cross-check 404s and aborts the whole install. pnpm install --trust-lockfile skips that check and installs cleanly; from there it's a normal pnpm approve-builds esbuild for esbuild's native postinstall, then pnpm build succeeds end to end.

Pushed a follow-up commit with a freshly built ui/dist (same two files the merged Arabic PR, #344, touched), so this should now be a complete, working locale contribution rather than partial.

[SID-6921]

@sox8502 @myles332 — this is my first PR here, so the CI/Release workflow runs are sitting at `action_required` and need a maintainer to approve them before they'll execute. Whenever you get a chance to approve the run (or let me know if anything else is needed), happy to address feedback.