store: set aside a torn last journal line on open; server waits for lock

A crash or power loss mid-append can leave a partial last line. The
writer acknowledges an append only after its whole line is synced, so
that line was never acknowledged: opening now saves those bytes to
journal.jsonl.torn.<time>, truncates to the last newline, and journals
journal.tail_repaired (replay and projection ignore it; the GUI shows
it; books.digest reports it in journal_repairs). Damage before the last
newline is still corruption and still refuses to open. Tested at every
byte of the last append.

The MCP server now waits up to ten seconds for the writer lock: a
restarted server (a client reconnecting) raced the exiting one and died
with Locked, which also made mcp_schedules_and_recurring_over_stdio
flaky. The test harness now waits for each server to exit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

crates/ledger-gui/src/pages/journal.rs

@@ -220,6 +220,11 @@ pub fn describe(b: &Books, line: &JournalLine) -> Option<Event> {
             format!("Recurring: {}", s(p, "description")),
             Some(Route::Company),
         ),
+        "journal.tail_repaired" => ev(
+            icon::WARNING,
+            format!("Cut-off journal line set aside ({} bytes)", p["bytes"]),
+            None,
+        ),
         "recurring.generated" => ev(
             icon::REPEAT,
             "Recurring draft created".into(),