Read a session's transcript as the file it is

The conversation on screen is a drawing of the record, and when the two
disagree -- or when something in the record is what has gone wrong -- there
was no way to see the record itself from the phone.

View raw in the session settings dialog opens the file explorer on the
transcript, which is its third caller and needed no new screen: the file
name and path in the header, a back button, and the lines as code. The
session says where the file is, because only the backend knows, and it
names this backend's machine rather than the session's -- for a remote
session those are two different filesystems. Back from the file lands in
the session's own directory, where the log and the process record are.

The paragraph under Reload goes, and both buttons move to a line of their
own: two buttons and a measurement do not fit a phone's width.

AGENTS.md

@@ -201,6 +201,12 @@ Module-by-module intent is in PLAN.md's "Backend layout".
   (`server/src/session/subagent.rs`, the subcards in `SessionListScreen.kt`
   and the read-only form of `SessionScreen.kt`); `DECISIONS.md` holds the
   choices made there that are still awaiting review.
+  **The transcript file itself is readable from the session settings dialog**
+  (2026-09-21): *View raw* opens the file explorer on it, from
+  `transcriptFile` on `GET /sessions/{id}` -- which names the machine *this
+  backend* runs on, not the session's. It is the explorer's third caller and
+  needed no new screen; a transcript past `FILE_LIMIT` (1 MiB) is refused the
+  way any other large file is.
 - `EXPLORER.md` — the file explorer's design (`server/src/files.rs` and
   `FilesScreen.kt` / `FileViewer.kt` / `FileEditor.kt`).
 - `TRANSCRIPT_CACHE.md` — the phone's copy of what it has been sent. Read it