[WEB] zh-CN greeting spliced from fragments + more hardcoded UI strings (i18n batch 3)

Description

Third pass of zh-CN i18n completions, follow-up to #9781 / #9782.

1. Greeting splicing bug

apps/web/core/components/home/user-greetings.tsx and apps/web/core/components/user/user-greetings.tsx render {t("good")} {t(greeting)}. This works for English ("Good afternoon") but concatenates nonsense in Chinese: zh-CN values are 「早上」+「下午」, producing 「早上 下午, 」.

Fix: replace the fragment keys good/morning/afternoon/evening with whole-phrase keys good_morning/good_afternoon/good_evening (en: "Good morning" etc.; zh-CN: 「早上好」「下午好」「晚上好」; zh-TW: 「早安」「午安」「晚安」; other locales mirror English per the sync-check contract). Both components now make a single t() call. The old keys have no other references and are removed.

2. More hardcoded English strings routed through i18n

User-facing leftovers found by static scan, high-traffic surfaces only:

• Module link modal (title, labels, placeholders, buttons, toasts — via existing common.* shared keys, mirroring the issue-detail link modal)
• Cycles "Transfer work items" modal: title, search placeholder, empty state, loading state, success/error toasts (new cycle.transfer_issues_modal.*)
• Delete/leave project confirmation modals: title, description, instructions (ICU {name}/{value}), placeholders, buttons, toasts (new project.modals.*). The typed confirmation literals (delete my project, Leave Project) intentionally stay English — they are compared against code constants.
• Project state create/update form: placeholders, cancel button, required validation
• Inbox issue properties: assignee / due date dropdown placeholders (new inbox_issue.properties.*)
• Pages list search input (new page.page_list.search_placeholder)
• Search boxes in cycles/modules/views headers, views filter panel, bulk-delete issues modal, inbox duplicate picker (reuse common.search.label)

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Environment

• Plane version: preview (post v1.4.2)
• Browser: any (locale-dependent)

Checklist

• I have searched existing issues to avoid duplicates (follow-up to #9781)

Start with apps/web/core/components/home/user-greetings.tsx and apps/web/core/components/user/user-greetings.tsx, then search the web surfaces listed in the issue for the remaining hardcoded strings and old greeting keys. Check the locale entries against the stated English, zh-CN, and zh-TW wording and the sync-check contract; done means the listed UI text is routed through i18n and the obsolete keys have no references.