Join every turn-final answer instead of only the last (Group A)

Pi drains queued follow-ups and steers inside the same run with no
agent_end/agent_start between them, so when a scheduled job's follow-up (or
a user steer) merges into a run, the model can answer twice before
agent_settled fires once. AgentHost.settle() used only the last assistant
message as finalText, so the first answer was lost (it only ever appeared
as progress-message narration, which gets deleted).

RunRecord now tracks `finals`: assistant texts whose stopReason is not
toolUse (and, as before, not error/aborted), collected alongside `texts`.
settle() joins `finals` with blank lines, falling back to `texts` and then
to the placeholder, matching the documented fallback chain.

Claude-Session: https://claude.ai/code/session_01JtuZTCMW9TyogEmBgGf8JT

docs/superpowers/specs/2026-09-06-volcanic-secretary-design.md

@@ -127,10 +127,11 @@ Mapping from Pi session events:
   - `stopReason` `error`: `run_error` with the message's `errorMessage`.
   - `stopReason` `aborted`: `run_settled` with `aborted: true` and empty
     `finalText`.
-  - Otherwise `run_settled` with `aborted: false`. `finalText` is the text of
-    that last message. If that is empty, it is all recorded assistant texts of
-    the run joined with blank lines. If still empty, it is "Done, no text
-    reply."
+  - Otherwise `run_settled` with `aborted: false`. `finalText` is every
+    assistant message in the run whose `stopReason` was not `toolUse`, joined
+    with blank lines, because Pi drains queued follow-ups and steers inside
+    the same run. If that is empty, it is all recorded assistant texts joined
+    with blank lines. If still empty, it is "Done, no text reply."
 - `status()` reads `session.isStreaming`, `session.model`,
   `session.thinkingLevel`, `session.getContextUsage()`, and
   `session.sessionFile`.