i18n parity, 12 new tool tests, smarter search, homepage tag filter

This update is about three things: non-Chinese user experience, test coverage, and finding tools on the homepage.

i18n

• en/ja/vi were missing 8 tool docs in total, so non-Chinese users saw a shorter tool list than the Chinese locale.
• We backfilled the missing chmod-calculator, dot-renderer, image-to-ico, cidr-calculator, csv-editor, password-generator, pdf-to-html, and random-username docs.
• All four locales now ship the same 77 tools. Clicking through the navbar on any locale shows an identical list.

Test coverage

• Previously we only had 47 test files / 135 assertions, with 32 tools untested.
• Added unit tests for 12 tools (7 ciphers, 2 network, 3 image/analysis):
  • Atbash / Rot13 involution round-trips
  • Caesar / Bacon / RailFence / Vigenere encode↔decode round-trips
  • Morse encode/decode plus space-to-slash handling
  • DnsLookup / SslCheck with mocked fetch covering empty-URL prompts and API success/failure paths
  • Pigpen / WordCloud with mocked canvas checking placeholder copy and disabled-state coupling
  • TextEncrypt covering empty-text and short-password warnings plus mocked encrypt success showing the shareable link
• Total: 47 → 59 test files, 135 → 177 assertions (with more to come).

Search experience

• The old search only did a naive substring match against title and description, so queries like "json 美化", "erweima", or "validator" returned nothing.
• A new src/utils/search.js scores matches across multiple fields and ranks by weight: title substring > title full pinyin > title pinyin initials > aliases > alias pinyin > description.
• We added an aliases frontmatter field to 23 popular tools (json-formatter, qrcode, timestamp, regex-tester, …), so queries like "二维码", "validator", or "时间戳" now hit.
• Matched title fragments are highlighted in yellow inside the result cards, so you can see exactly what matched.
• Fixed a P2 bug where the homepage "Search" button had no onClick handler — clicking it now focuses the input.

Homepage discoverability

• 70+ tools on one long scroll was painful for newcomers.
• A new "purpose" tag bar sits at the top of the tools section (Converter, Generator, Encoder, Decoder, Formatter, Validator, Calculator, Lookup, Cipher, Editor, Security, Compressor). Click it to filter across categories, with counts next to each tag.
• Category headers are now collapsible — click to fold/unfold, with an up/down chevron and a count badge.
• When a purpose tag is selected, "Favorites" and "Recently used" automatically step aside and only tools matching the selected purpose remain.

Bug fix

• The timestamp tool test was flaky around the 0:00 boundary when the current year showed up in multiple description values; switched to getAllByText to make it deterministic.

Let us know in the comments below if the new search feels right for you.