feat(clients): support setting HWID limit and MTProto ad-tag in bulk adjust (#6399)

* feat(clients): support setting HWID limit and MTProto ad-tag in bulk adjust

Add HWID device limit and Telegram MTProto sponsor channel (ad-tag)
support to the bulk client adjustment flow in both the panel API
and frontend ClientBulkAdjustModal.

Co-Authored-By: Claude Code <noreply@anthropic.com>

* fix(clients): gate adTag to MTProto inbounds and avoid inbound rewrite for limitHwid

Co-Authored-By: Claude Code <noreply@anthropic.com>

* fix(clients): stamp updated_at only on the clients a bulk adjust changed

The updated_at write was gated on hasInboundChanges, which accumulates
over the whole inbound instead of describing the client in hand. Once any
client in the settings array changed, every client after it was re-stamped
as well, so whether an untouched client kept its own updated_at depended on
its position in the array. That field feeds node-snapshot conflict
resolution, where a spurious bump lets a stale snapshot value win over the
stored record.

Track the change per client and fold it into the inbound-level flag where
the stamp is written, so the early return still skips a save whose settings
JSON would be unchanged.

Also condenses the BulkAdjust doc comment back to the two-line maximum.

* docs(api): regenerate the bulkAdjust reference for limitHwid and adTag

frontend/public/openapi.json was copied to docs/public/, but pnpm gen:api
was never re-run, so the API reference page's heading, anchor id and search
index still described bulkAdjust without limitHwid or adTag. docs-ci.yml
fires only on docs/**, and that path had been touched, so nothing flagged
the stale MDX.

The externalLinks hunks are the generator rewrapping lines main had left
stale, not a content change.

* fix(i18n): stop enumerating fields in the bulk-adjust empty-form message

bulkAdjustNothing listed the fields the form accepts, so it went stale
every time one was added: only en-US ever gained "flow", leaving the other
twelve locales describing days and traffic alone, and limitHwid and adTag
would have repeated that. Say that one field is required instead of naming
which, so the message cannot drift again.

internal/web/translation/en-US.json

@@ -846,7 +846,7 @@
       "bulkDeleteConfirmContent": "Each selected client is removed from every attached inbound and its traffic record is dropped. This cannot be undone.",
       "bulkAdjustTitle": "Adjust {count} clients",
       "bulkAdjustHint": "Positive values extend, negative values reduce. Clients with unlimited expiry or traffic are skipped for that field.",
-      "bulkAdjustNothing": "Set days, traffic, or flow before applying.",
+      "bulkAdjustNothing": "Set at least one field before applying.",
       "addDays": "Add days",
       "addTrafficGB": "Add traffic (GB)",
       "bulkFlow": "Set flow",
@@ -912,7 +912,8 @@
       "renewMaxDesc": "How many times auto-renew may fire before the client is left to expire. 0 means no limit. Catching up several missed periods spends one renewal per period.",
       "renewOnDay": "Renew on day",
       "renewOnDayDesc": "Renew on this day of every calendar month, at midnight in the panel's time zone, instead of every N days. A month too short for the chosen day renews on its last day. 0 keeps the day-interval mode.",
-      "renewsUsed": "Renewals used"
+      "renewsUsed": "Renewals used",
+      "bulkAdTagHint": "Enter a 32-character hex tag to set, or 'none' to clear sponsor channel on MTProto inbounds."
     },
     "groups": {
       "name": "Name",