Let the install set how many steps a run may take

The two limits were compiled in: a task run stopped at
AppData.HarnessMaxToolSteps (200) and a chat reply at
AppData.BotReplyMaxToolSteps (8), so an install that needed a longer task
had to rebuild.

Both are now `app_settings` rows (`harness_max_tool_steps` and
`bot_reply_max_tool_steps`), read at the two loop call sites through
grabHarnessMaxToolSteps and grabReplyMaxToolSteps, and edited by the super
admin on Settings > General beside the prompt appendix. Zero clears a
limit back to the code default, like the bot file quota.

readStepLimit keeps the saved number only when it is a whole number of at
least 1 and no more than AppData.BotStepLimitMax (1000), so a blank, a
zero or a typo falls back instead of stopping every run before its first
turn, and a huge number still ends in the wrap-up report.

runTextLoop keeps AppData.HarnessMaxToolSteps as its default, so it stays
free of database reads and its tests run as they did.

src/data/app-data.ts

@@ -246,7 +246,10 @@ export const AppData = {
     HarnessCooldownMs: 60 * 1000,
     HarnessMaxCooldownMs: 24 * 60 * 60 * 1000,
     /**
-     * Model turns in one text run before it must stop and report.
+     * Model turns in one text run before it must stop and report. The
+     * install may save its own limit (the `harness_max_tool_steps` setting,
+     * Settings > General), which wins over this one; a task run reads it
+     * through `grabHarnessMaxToolSteps`.
      */
     HarnessMaxToolSteps: 200,
     /**
@@ -389,8 +392,17 @@ export const AppData = {
     WorkspaceActivityItems: 6,
     /**
      * Tool turns a chat reply may take. Long work goes to a task instead.
+     * The install may save its own limit (the `bot_reply_max_tool_steps`
+     * setting, Settings > General), which wins over this one; a reply
+     * reads it through `grabReplyMaxToolSteps`.
      */
     BotReplyMaxToolSteps: 8,
+    /**
+     * The most steps a saved run limit may ask for, for a task run or a
+     * chat reply. A typo in the settings page can't turn one run into an
+     * hour of tool calls, and a huge limit still ends with a report.
+     */
+    BotStepLimitMax: 1000,
     /**
      * Chat attachments: per file, per message, and how much of a
      * document's text a reply reads.