fix(i18n): add key-coverage guard, pseudo-locale, and convert Connect…

[Chigybillionz]

PR Description

// markdown

Fix: Add i18n key-coverage guard, pseudo-locale, and convert ConnectWalletModal

Summary

This PR addresses issue #1389 by adding audit, guard, and second-locale infrastructure to the i18n layer, and converting the largest hardcoded-string cluster (ConnectWalletModal) as a proof of concept.

Issue

Closes #1389

Root Cause

The i18n layer had infrastructure (typed keys, interpolation, pluralization) but no mechanism to detect when components bypass it. With only one locale (English), missing keys silently fall back to English — making the gap invisible until a second locale is added.

Solution Implemented

Audit Result

• 250 i18n-routed keys in en.ts
• ~620+ hardcoded user-facing strings across 71 source files
• Largest clusters: ConnectWalletModal (~60+), Streams detail (~40+), Treasury overview (~30+), Recipient portal (~20+)

Guard Mechanism: Key-Coverage Test

A new test (src/i18n/__tests__/keyCoverage.test.ts) that:

• Scans all .tsx/.ts files under src/ (excluding tests and i18n itself)
• Extracts strings from JSX text content, aria-label, placeholder, title, alt, label, description attributes
• Reports strings that already have i18n keys but aren't wired (known backlog — warning only)
• Reports strings NOT in the catalog at all (currently console.warn; TODO: switch to hard fail once backlog is resolved)
• Runs as part of npm run test — no ESLint infrastructure needed

Why a test, not an ESLint rule: The lint gate is currently disabled for a documented backlog. A rule that can't run provides zero protection. The test runs unconditionally via vitest.

Second Locale: Pseudo-Locale (zx)

A pseudo-locale (src/i18n/zx.ts) that transforms every string to [Čřéáţé şţŕéáм]. When activated (set locale="zx" on I18nProvider):

• Properly translated strings appear with [...] markers and accented characters
• Hardcoded strings appear WITHOUT markers — making missing keys immediately visible
• Interpolation placeholders {token} are preserved unchanged

Bounded Conversion: ConnectWalletModal

Converted ~60 hardcoded strings to t() calls across all wallet connection states:

• Default view (wallet selection, terms)
• Not installed / Rejected / Network mismatch / Timeout error states
• Hardware wallet flow (device searching, device found, awaiting confirmation)
• Hardware error states (locked, wrong app, unplugged, mobile unsupported)

English rendering is functionally identical.

Key Changes

• src/i18n/en.ts — Added ~110 connectWallet.* translation keys
• src/i18n/index.tsx — Registered "zx" pseudo-locale, imported createPseudoLocale
• src/i18n/zx.ts — New — pseudo-locale with character transformation
• src/components/ConnectWalletModal.tsx — Converted ~60 hardcoded strings to t() calls
• src/i18n/__tests__/keyCoverage.test.ts — New — key-coverage guard test
• src/i18n/__tests__/pseudoLocale.test.ts — New — 16 tests for pseudo-locale
• src/components/__tests__/ConnectWalletModal.stateMachine.test.tsx — Updated test for interpolated text node

Trade-offs / Considerations

• The key-coverage guard currently warns (not fails) because there are ~571 existing hardcoded strings. Once the backlog is resolved, it should be switched to a hard fail.
• The network mismatch description lost <strong> tags around network labels due to i18n interpolation (minor visual difference).
• The pseudo-locale is a developer tool — not meant for end users. It's wired into the Locale type but not exposed in any UI menu.

Testing

• npx vitest run src/i18n — 62/62 passed (including 16 new pseudoLocale tests, 3 new keyCoverage tests)
• npx vitest run src/components/__tests__/ConnectWalletModal — 47/47 passed
• npx tsc --noEmit — no errors in changed files

CI Verification

• npm run test src/i18n — passed
• npx tsc --noEmit — passed (pre-existing errors in unrelated files remain)

Remaining Areas for Follow-up

Priority	Area	Files	Est. strings
High	Streams detail	Streams.tsx	~40+
High	Treasury overview	ActivityHeatmap.tsx, RecentStreams.tsx, StreamsTable.tsx, etc.	~30+
High	Recipient portal	Recipient.tsx	~20+
Medium	Treasury onboarding	TreasuryOnboarding.tsx	~15+
Medium	Navigation/Layout	AppNavbar.tsx, Layout.tsx, Navbar.tsx, Footer.tsx	~10+
Medium	CSV upload	ColumnMappingStep.tsx, PreviewValidateStep.tsx	~10+
Low	Remaining ~20 files	Various	~130+

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Please review this task. If there are any corrections, improvements, or adjustments needed, I'd appreciate your feedback. Thank you!