feat(xray): browse geosite/geoip categories from routing rules (#6165)

* feat(xray): browse geosite/geoip categories from routing rules

Routing rules made you type category names from memory: nothing showed which
categories a database actually contains, what is inside one, or whether a
name resolves at all — a typo only surfaced when Xray refused the config.

The panel now reads Xray's .dat databases itself and exposes them over four
endpoints: databases in the asset folder, a database's categories, one page
of a category's rules, and validation of the tokens already in a rule. The
reader walks the protobuf wire format directly rather than decoding into Go
structs, because a 10 MB geosite.dat holds well over a million domains and
materialising them costs ~284 MB where streaming costs ~19 MB. Only the
category index is cached, entry pages are scanned on demand, and scans are
serialised, so twenty concurrent requests peak at 87 MB instead of 1 GB.
A database's type is decided by its contents, not its file name, since
custom .dat files are named freely.

In the rule form, the source-IP, IP and domain fields gain a database button
opening the browser: search over categories, a preview of what a category
holds, and a multi-select that merges into the field. Plain domains, CIDRs
and categories the panel does not know are left untouched; categories already
present come back ticked, and unticking one removes it from the rule.

* fix(xray): read geo databases through os.Root and match codes verbatim

CodeQL flagged the database read as a path built from a user-supplied value,
and it was right about the shape of it. The file name arrives in a request;
resolve() rejects traversal and stats the file through an os.Root, but the
read itself went through a joined path with os.ReadFile. That left the
symlink defence incomplete: the stat could pass while the read followed a
link planted — or swapped in — afterwards.

Reads now go through the same root, so a request-supplied name never becomes
a path this code resolves on its own, and the size limit is applied to the
opened file rather than to a separate stat of it.

Lookup no longer trims the category code either. It backs the routing-token
validator, and the core matches codes verbatim: "geosite: cn" will not start
Xray, so repairing that space here hid exactly the typo the validator exists
to report.

* fix(xray): address review findings on the geo category browser

Asset folder. The browser read config.GetBinFolderPath() unconditionally,
but the core honours a preset XRAY_LOCATION_ASSET and only falls back to the
bin folder (ensureXrayAssetLocation). On an install pointing at a shared
asset directory the panel listed an empty folder and reported perfectly
valid geosite:/geoip: tokens as missing — the validator warning about a
correct config. The directory is now resolved with the core's precedence.

Paging. Serving one page read and rescanned the whole database, so walking
category-ads-all re-read it per page. The index now records each category's
byte range and a page reads only that record through the os.Root handle,
with the current category's records held for the duration of a paging
session. Profiling that also showed the real cost was not the read but the
slice of payload pointers built per call — a category holds a hundred
thousand of them — so records are now walked with a callback instead.
Ten pages over category-ads-all: 239 MB allocated, now 4.3 MB.

Cached failures. Any error from reading a file was latched under the file's
size+mtime, so a transient ENOMEM or EMFILE marked a healthy database as
damaged until it changed on disk. Only deterministic failures are cached.

Wrong kind. A geoip: token typed into a domain field parsed as a plain
domain and was waved through, though the core cannot resolve it as one. It
is now reported, with its own reason and wording.

Frontend. The category filter fed the query key on every keystroke, so each
character triggered a request that re-scanned the database; it is debounced
now. GeoTokenInput accepts and forwards a ref, so React Hook Form can focus
these three fields on a validation error again. A failed validation shows
that it failed instead of rendering the same empty state as "no issues".

Also drops an unreachable branch in the token-count guard and corrects the
categories endpoint docs, where limit is unbounded by default.

---------

Co-authored-by: STRENCH0 <17428017+STRENCH0@users.noreply.github.com>

internal/web/translation/zh-TW.json

@@ -1446,6 +1446,35 @@
       "routing": {
         "dragToReorder": "拖曳以重新排序"
       },
+      "geoBrowser": {
+        "title": "geo 分類",
+        "openTooltip": "瀏覽 geo 分類",
+        "database": "資料庫",
+        "searchCategory": "搜尋分類",
+        "searchEntries": "在分類內篩選",
+        "selectFound": "勾選搜尋結果",
+        "selected": "已選 {count} 項",
+        "clearAll": "全部清除",
+        "apply": "套用",
+        "emptySelection": "勾選分類，它們將成為規則中的項目",
+        "pickCategory": "在左側選擇一個分類以查看其內容",
+        "noMatches": "找不到任何內容",
+        "noFiles": "Xray 目錄中沒有 geo 資料庫",
+        "noFilesHint": "Xray 下載 geosite.dat 與 geoip.dat 後即會出現",
+        "fileMeta": "{count} 個分類 · {size} · 更新於 {date}",
+        "entriesCount": "{count} 筆記錄",
+        "subnetsCount": "{count} 個網段",
+        "shownRange": "顯示第 {from}–{to} 項，共 {total} 項",
+        "loadFailed": "無法載入 geo 資料庫",
+        "checkFailed": "無法依據 geo 資料庫檢查這些值",
+        "parseFailed": "檔案已損毀或不是 geosite/geoip 資料庫",
+        "tooLarge": "檔案過大，無法瀏覽",
+        "unknownCategories": "資料庫中不存在：{tokens}",
+        "missingDatabase": "找不到資料庫檔案：{tokens} — 請在 Geodata 中新增",
+        "unknownAttribute": "找不到該屬性，規則不會比對到任何內容：{tokens}",
+        "invalidToken": "Xray 無法接受此寫法：{tokens}",
+        "wrongKind": "此欄位的資料庫類型不符：{tokens}"
+      },
       "ruleForm": {
         "sourceIps": "來源 IP",
         "sourcePort": "來源連接埠",