feat(core,ui): in-app browser (platform wrapper) detection

[Sanka-D]

Part 3/4 of closing the Stellar-Wallets-Kit feature gap. Additive & backward compatible.

Gap #1 — no in-app browser detection

When a user opens a dApp from inside a mobile wallet's built-in browser, xrpl-connect had no way to know, so it couldn't surface that wallet first. SWK exposes an optional per-module isPlatformWrapper() for exactly this.

Fix (faithful port of SWK's optional-method design)

• WalletAdapter.isPlatformWrapper?() — optional; an adapter returns true when the dApp is running inside its in-app browser.
• WalletManager.getPlatformWrapper() — returns the first adapter reporting true. Each check is bounded by TIME.PLATFORM_WRAPPER_TIMEOUT (500 ms, matching SWK) so a slow adapter can't delay detection; adapters without the method are skipped.
• <xrpl-wallet-connector> — on open, detects the wrapper and promotes it to the top of the list, unless an explicit primary-wallet attribute is set (that still wins).

As in SWK, isPlatformWrapper is an optional per-wallet method — this PR lands the mechanism + manager/UI wiring; individual wallets opt in by implementing it (no bundled adapter ships a verifiable in-app-browser signal today, so none is fabricated here).

Changes

• packages/core/src/types.ts — optional isPlatformWrapper() on WalletAdapter.
• packages/core/src/constants.ts — TIME.PLATFORM_WRAPPER_TIMEOUT.
• packages/core/src/wallet-manager.ts — getPlatformWrapper().
• packages/ui/src/wallet-connector.ts — detect on open + promote (falls back to primary-wallet).
• packages/core/tests/wallet-manager.test.ts — +3 tests (detect / none / timeout).

Verification

• pnpm build (full workspace, 13/13) ✅
• pnpm test — core 16 passed (+3), ui 4 ✅
• pnpm lint ✅ · prettier --check ✅

🤖 Generated with Claude Code

[RomThpt]

Review: feat(core,ui): in-app browser (platform wrapper) detection

Verdict: approve_with_nits — CI green (docs-build + test-and-build)

Points positifs

• Implementation soignee, pattern capability conforme a develop.
• 3 tests manager solides (adapter detecte, null quand aucun, timeout fake timers).
• Purement additif, semver-minor.

Nits

• Detection sequentielle apres availability checks : getPlatformWrapper() (line 369) ne commence qu apres les isAvailable(), ajoutant jusqu a +500ms au premier open. Pourrait etre lance en parallele.
• Timeout timer jamais clear (line 286) : setTimeout dans Promise.race non capture/clear quand l adapter gagne.
• Empty primary-wallet attribute (line 775) : getAttribute("primary-wallet") ?? this.detectedWrapperId ne traite pas "" comme unset -> suppression promotion detectee.
• Docs non mises a jour : getPlatformWrapper() et isPlatformWrapper() absents de docs/guide/api-reference.md et adapter-integration.md.

Tests

Manque : path rejection (isPlatformWrapper throw), first-match ordering, et tout test UI pour la promotion logic.

[Sanka-D]

Pre-live review: the abstraction and timeout are reasonable, but no adapter in this PR implements isPlatformWrapper. The feature has no observable production effect. Recommendation: keep it out of the release until at least one real adapter implementation and browser-specific tests are included.

[Sanka-D]

Closing for the pre-live merge train: this PR adds the isPlatformWrapper() abstraction, but no production adapter implements it, so it currently has no observable effect. It can be reopened or replaced once it includes a real adapter implementation and browser/mobile regression tests.