fix(ui): replace code identifiers in the English stat-card copy

[argszero]

Summary

The English language pack rendered four stat-card sub-labels as raw code identifiers, where the Chinese pack carries proper prose. In the UI this is directly visible as a database dump next to ordinary English copy.

key	before (EN)	after (EN)	zh (unchanged, for reference)
ops.stats.keys.sub.on	status=on	enabled	启用状态
ops.stats.calls.sub	usage_records	usage records	用量记录
admin.emp.stats.admins.sub	role=admin	admin role	管理员角色
admin.emp.stats.deps.sub	organization	organization management	组织管理

Rendered before/after (EN, ops view):
...Active keys 5 status=on Calls this month 900 usage_records Points in ...
→ ...Active keys 5 enabled Calls this month 900 usage records Points in ...

(EN, admin members stats):
...Admins 1 role=admin Departments 0 departments organization
→ ...Admins 1 admin role Departments 0 departments organization management

The last one had a second problem: the sub-label organization sat directly under the value of the adjacent Departments card, which itself reads 0 departments — so the two cards read as one broken sentence. organization management matches the sidebar tab label and separates cleanly.

Related Issue

None — the repository has no open issues. This was found by a runtime audit of the language packs and reported here.

Changes

• ui/js/i18n.js — 4 English values rewritten to natural copy (zh pack byte-identical)
• ui/index.html — cache-bust ?v=20260911-12 → -13 (5 references)
• No key added/removed, no placeholder or structure change: 775 == 775, 0 only-in-zh, 0 only-in-en, 0 placeholder mismatches

Scope note: this PR intentionally changes English copy only. Two neighbouring items were deliberately not touched, to keep the change single-purpose and reviewable:

• admin.usage.unit.yuan = yuan and the adjacent calls unit labels (romanization / bare units). Whether English should read yuan or CNY depends on how the admin models table presents currency (admin.models.col.in = Input $), which is a modelling question, not a translation slip. Worth a separate discussion.
• admin.models.col.in/out = Input $ / Output $ — the backend stores a per-model currency, so a hardcoded $ may be wrong for the CNY rows.

Tests

• cargo test — 148 passed, 0 failed
• cargo fmt --check — clean
• cargo clippy --all-targets -- -D warnings — clean
• New/updated unit tests (if applicable) — not applicable: this is a language-pack value change, covered by the existing i18n parity gate

Verification evidence

i18n gate on the Node-evaluated real module: 775 == 775, 0 only-in-zh, 0 only-in-en, 0 placeholder mismatches.

A/B runtime harness, baseline (git archive HEAD ui) vs this branch, both built by the same generator, headless Chrome, measuring the .sub element of each stat card:

• EN ops: ['platform service OK', 'all registered users', 'status=on', 'usage_records', ...] → ['...', 'enabled', 'usage records', ...]
• EN admin: ['real users', 'balance + gift', 'role=admin', 'organization'] → ['...', 'admin role', 'organization management']
• Negative control: the four identifiers are asserted present in the baseline, so "gone" is not vacuous
• Regression control (zh): the rendered Chinese stat cards are asserted identical before and after ⇒ the change provably touches only the English pack
• No CJK leaked into EN in any measured pane

Checklist

• Branch name follows the convention (fix/...)
• Commit message uses Conventional Commits (fix(ui): ...)
• Single responsibility, minimal change (2 files, +9/−9)