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/dict/harness-dict.ts

@@ -53,6 +53,12 @@ export const Harnesses = [
 
 export type HarnessKind = (typeof Harnesses)[number]["value"];
 
+/**
+ * The `app_settings` key holding the install's own limit on model turns in
+ * one run (a task). Unset means `AppData.HarnessMaxToolSteps`.
+ */
+export const HarnessMaxToolStepsSettingKey = "harness_max_tool_steps";
+
 /**
  * Vendors preferred for automatic picks, best first. Free models from any
  * other vendor come after these, and only if they look competent.