fix(log): bdrive log reads as a timeline — newest first by edit time (#BEA-40) (#90)

`bdrive log` sorted by the lamport clock, so the wall-clock stamps it prints
came out non-monotonic — two 06:09:24 rows above a 06:10:00 row. And every op
of one scan is stamped with that scan's commit time, so a 22-file agent run
collapsed onto a single stamp. Neither is readable as a timeline, which is the
whole job of the command.

Two display-only changes:

- `journal.Op` gains `Mtime` (`omitzero`, so old journals and old binaries are
  unaffected), populated on put ops from the `os.FileInfo` the scan already
  holds. Deletes and conflict copies keep their commit time.
- `syncer.DisplayTime` / `SortForDisplay` order by the timestamp that is
  actually printed, ties broken by reversed `journal.Less`. `bdrive log` sorts
  and *then* truncates, so `-n 25` is the 25 newest by that stamp.

`journal.Less`, `Sort`, and `Replay` are untouched — replay order is the
convergence contract, so the sort lives in `syncer`, not in `journal`.
`LogEntries` also keeps returning causal order because `bdrive restore` walks
it to find a file's previous version.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/docs/src/content/docs/reference/cli.md

@@ -24,7 +24,7 @@ One binary, `bdrive` — the CLI, the sync daemon, and the web server.
 | `bdrive hooks [install\|uninstall]` | Register turn-boundary sync hooks in each detected agent platform's user config — once per machine, covering every folder. Run automatically by `bdrive init`; idempotent; `--agent` overrides detection. `uninstall` removes only BearDrive's own hook entries |
 | `bdrive read-log [folder]` | Hook plumbing: queue agent file reads for the hub's read heatmap. Registered by `bdrive hooks install` |
 | `bdrive status [folder]` | Projects, daemon state, pending changes |
-| `bdrive log [folder] [-p path] [-n N]` | Change history: account, device, time, file |
+| `bdrive log [folder] [-p path] [-n N]` | Change history: account, device, time, file — newest first by the time shown, which is when the file was written (ops recorded before this was tracked, and deletes, show their sync time instead) |
 | `bdrive restore <file> [version]` | Put an earlier version of a file back, as a new change. No version restores the previous one; `--list` shows the versions with their short hashes |
 | `bdrive export [folder]` | Export the whole project — all devices' history and content — to a portable `.tar.gz` (`-o` names the file) |
 | `bdrive import <archive>` | Import an export archive as a new project on the hub you're logged into (`--name` overrides the archive's name) |