feat(files): let the path picker jump to a typed path and sort by name or date

The picker's current-folder line was a read-only breadcrumb, so reaching a
deep folder meant tapping through every level, and the listing was fixed to
name order, so the file an agent had just written was somewhere in a
500-entry list.

The current folder is now an editable field: Enter or Go jumps there, a full
file path lands in its folder with that file selected, and a path that does
not resolve keeps the listing you had and says so, instead of the reset to
the root that a stale initialPath gets. A Sort control orders the listing by
name or modified time in either direction, folders always first, and the
choice is remembered per device like the hidden toggle. Each entry shows a
compact modified time (time of day today, month-day this year, else the
date).

GET /api/filesystem/browse stamps every entry with mtimeMs to make that
possible; the stat that already fetched a file's size now serves both, so
it is still one stat per entry. Entries without an mtime (an older server,
the in-container listing) sort after dated ones and then by name.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01McLWqCWBuQYGuPMScb4Aou

docs/wiki/Working-With-Files.md

@@ -117,10 +117,14 @@ For choosing a path rather than typing one. It appears in two places:
 - **Browse** in **Add Case → Link Existing**.
 - The **📁 Path** key on the mobile keyboard bar.
 
-It browses one directory at a time and can show hidden entries on request. The picker
-inserts the path into your prompt **without** pressing Enter, so nothing is submitted by
-accident. Its sibling **⌫ All** key clears the unsent prompt, and never sends the agent's
-`/clear` command.
+It browses one directory at a time and can show hidden entries on request. The current
+folder is an editable field: type or paste a path and press Enter (or **Go**) to jump
+straight there, and a full file path lands in its folder with that file selected. The
+**Sort** control orders each listing by name or by modified time (newest first is the
+quick way to the file an agent just wrote), with folders always ahead of files; the
+choice is remembered per device. The picker inserts the path into your prompt
+**without** pressing Enter, so nothing is submitted by accident. Its sibling **⌫ All**
+key clears the unsent prompt, and never sends the agent's `/clear` command.
 
 This is a separate file-serving surface from the viewer, with its own rules: it allowlists
 your home directory, the cases directory, and anything in `CODEMAN_FILE_PICKER_ROOTS`, and