feat(settings): data-safe editors, deep-linked search, Data/About/Cost pages

- EditorModal loads once per path (a parent re-render no longer reloads the
  file over the user's typing), refuses Save after a failed load, opens a
  truncated (>256 KB) file read-only, and asks before overwriting a file
  that changed on disk or could not be re-read.
- Settings/Hooks editors unset only keys from the snapshot taken at Edit,
  warn when the file changed underneath, keep a renamed key's value, and
  refuse a new key named like a redacted one (env) or a read-only hook
  event, which used to replace the secret/hooks.
- Project scope shows its resolved folder and is disabled inside the
  plugin cache. Account-profile, pricing-row and pet deletes confirm;
  two-click actions disarm after 3 s; unsaved drafts ask before closing.
- Search indexes every Claude Code / Codex sub-tab, opens it via ?tab= and
  scrolls to + highlights the row; the active config tab is in the URL.
- General splits into General / Data / About; Pricing moves to a Cost
  group with one shared load; config tabs group as Content / Extensions /
  Config with arrow-key roving; Promise.allSettled per tab.
- Data: browser-preferences export/import (allowlisted keys), per-section
  reset, housekeeping dry-run first, clear-all behind a typed phrase.
  Server: purge days must be a whole number >= 1 (INVALID_PURGE_DAYS) and
  dry_run returns exactly what the real run would delete.
- Alerts can be edited; webhooks/alerts/remote-source failures toast;
  copies go through copyText; modals get dialog roles and useDialog.
- Sagi: Ctrl/Cmd+B only when shown and not typing, default spot clear of
  row controls, arrow keys move it, reduced motion honoured; the dead
  /run launch link goes to the workspace.

client/src/i18n/locales/en/alerts.json

@@ -64,7 +64,11 @@
       "minutesStatus": "Fire when an agent stays in the selected status with no activity for this many minutes (a stuck agent).",
       "totalTokens": "Fire when a session's cumulative tokens (input + output + cache read + cache write) cross this number. e.g. 1000000 = 1M tokens.",
       "cooldown": "Minimum seconds between repeat alerts for the same rule + session + agent. Prevents noisy duplicates. Default 300 (5 min); 0 = no cooldown."
-    }
+    },
+    "edit": "Edit rule",
+    "save": "Save rule",
+    "typeFixed": "A rule's type cannot be changed — create a new rule instead.",
+    "cooldownInvalid": "Enter a whole number of seconds (0 or more)."
   },
   "feed": {
     "title": "Alert feed",
@@ -76,5 +80,12 @@
     "emptyTitle": "No alerts",
     "emptyDescription": "Alerts fired by your rules will appear here in real time.",
     "emptyUnacked": "Everything is acknowledged. New alerts will appear here as they fire."
+  },
+  "errors": {
+    "loadRules": "Could not load alert rules: {{error}}",
+    "loadAlerts": "Could not load alerts: {{error}}",
+    "toggleRule": "Could not change the rule: {{error}}",
+    "deleteRule": "Could not delete the rule: {{error}}",
+    "ack": "Could not acknowledge: {{error}}"
   }
 }