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.

server/routes/settings.js

@@ -357,18 +357,35 @@ homeRoutes("/claude-home", "CLAUDE_HOME", "claude_home", getClaudeHome, setClaud
 // into the current home at its spawn, so a move needs no repair here.
 homeRoutes("/codex-home", "CODEX_HOME", "codex_home", getCodexHome, setCodexHome);
 
-// POST /api/settings/cleanup — abandon stale sessions, purge old data
+// POST /api/settings/cleanup — abandon stale sessions, purge old data.
+// `purge_days` is a whole number ≥ 1 (0.1 days would purge almost everything);
+// `dry_run: true` answers the same counts and changes nothing.
 const PURGE_CHUNK = 500;
 router.post("/cleanup", (req, res) => {
   const { abandon_hours, purge_days } = req.body;
+  const dryRun = req.body.dry_run === true;
+  if (purge_days !== undefined && purge_days !== null) {
+    if (!Number.isInteger(purge_days) || purge_days < 1) {
+      return res.status(400).json({
+        error: {
+          code: "INVALID_PURGE_DAYS",
+          message: "purge_days must be a whole number of days, 1 or more",
+        },
+      });
+    }
+  }
   const result = { abandoned: 0, purged_sessions: 0, purged_events: 0, purged_agents: 0 };
+  if (dryRun) result.dry_run = true;
+  // A dry run abandons nothing, so the purge below would not see the sessions a
+  // real run abandons first and then purges; it adds them back from this list.
+  let wouldAbandon = [];
 
   if (abandon_hours && typeof abandon_hours === "number" && abandon_hours > 0) {
     // Mark active sessions with no recent events as abandoned
     const cutoff = new Date(Date.now() - abandon_hours * 3600 * 1000).toISOString();
     const stale = db
       .prepare(
-        `SELECT s.id FROM sessions s
+        `SELECT s.id, s.started_at FROM sessions s
          WHERE s.status = 'active'
            AND s.started_at < ?
            AND NOT EXISTS (
@@ -380,17 +397,22 @@ router.post("/cleanup", (req, res) => {
     const abandon = db.prepare(
       "UPDATE sessions SET status = 'abandoned', ended_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now') WHERE id = ?"
     );
-    // Also complete any lingering agents
-    const complete = db.prepare(
-      "UPDATE agents SET status = 'completed', ended_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now') WHERE session_id = ? AND status IN ('waiting','working')"
-    );
-    db.transaction(() => {
-      for (const row of stale) {
-        abandon.run(row.id);
-        complete.run(row.id);
-      }
-    })();
-    result.abandoned = stale.length;
+    if (dryRun) {
+      result.abandoned = stale.length;
+      wouldAbandon = stale;
+    } else {
+      // Also complete any lingering agents
+      const complete = db.prepare(
+        "UPDATE agents SET status = 'completed', ended_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now') WHERE session_id = ? AND status IN ('waiting','working')"
+      );
+      db.transaction(() => {
+        for (const row of stale) {
+          abandon.run(row.id);
+          complete.run(row.id);
+        }
+      })();
+      result.abandoned = stale.length;
+    }
   }
 
   if (purge_days && typeof purge_days === "number" && purge_days > 0) {
@@ -402,6 +424,27 @@ router.post("/cleanup", (req, res) => {
       )
       .all(cutoff);
 
+    if (dryRun) {
+      // Exactly the ids the real run deletes: those already purgeable, plus
+      // the stale ones it abandons first that are also older than the cutoff.
+      const ids = [
+        ...toDelete.map((r) => r.id),
+        ...wouldAbandon.filter((r) => r.started_at < cutoff).map((r) => r.id),
+      ];
+      for (let i = 0; i < ids.length; i += PURGE_CHUNK) {
+        const chunk = ids.slice(i, i + PURGE_CHUNK);
+        const placeholders = chunk.map(() => "?").join(",");
+        result.purged_events += db
+          .prepare(`SELECT COUNT(*) AS n FROM events WHERE session_id IN (${placeholders})`)
+          .get(...chunk).n;
+        result.purged_agents += db
+          .prepare(`SELECT COUNT(*) AS n FROM agents WHERE session_id IN (${placeholders})`)
+          .get(...chunk).n;
+      }
+      result.purged_sessions = ids.length;
+      return res.json({ ok: true, ...result });
+    }
+
     // One transaction, in chunks: a single IN (...) list of every id would
     // pass SQLite's bound-variable limit on a large history.
     db.transaction(() => {