yoda: cosmic-files customizations (squashed 21 commits)

This commit squashes the 21 local commits that customize cosmic-files for
the yoda stack, to allow a clean rebase on upstream/master.

Original commits (chronological):

- 9bcfe7a Cargo.toml: patch libcosmic via local path for dev builds
- 04abd13 yoda: depend on libcosmic-yoda (path) instead of upstream libcosmic
- 02adcc3 lockfile: libcosmic-yoda 0.1.0-yoda -> 0.1.0-yoda.2
- a025fd6 yoda: prefer cosmic-yoterm over upstream cosmic-term in terminal fallback
- e8d62ae yoda: add "Always use this app" toggle to OpenWith dialog
- 8fb2b15 yoda wayland-v5: redirect window_clipboard + cosmic-text to local forks
- 0595296 yoda: Dolphin-style quick actions toolbar under the headerbar
- 4b6d345 yoda: fix missing rename icon in toolbar
- 8b51af1 yoda: use pencil-symbolic for the Rename toolbar button
- 33a5c8f yoda: phase 2 - customizable toolbar (settings toggles per button)
- 1cf17dc yoda: phase 3 - drag-drop toolbar editor in Settings
- 11d4357 yoda: add up/down buttons next to drag handle in toolbar editor
- af843d2 yoda: direct drag-drop reorder on the toolbar itself
- 94c3e6c yoda: toolbar as segmented_button for working drag reorder
- f053819 yoda: toolbar icon-only + clean visual (Control style, 32px squares)
- 338354c Improve initial directory listing latency
- d080bc8 Resolve cosmic-files warnings without masking
- 69c35ab yoda: switch window_clipboard patch to public Forgejo fork
- 35e115f yoda: switch cosmic-text patch to public Forgejo fork
- 6f3adcd chore: clean feature-gated warnings
- 57ab1ec fix: clean files warnings for terminal build

Original tip preserved as tag backup/pre-rebase-upstream-20260524.

docs/local-performance-and-portal-notes.md

@@ -0,0 +1,78 @@
+# Local performance and portal notes
+
+Date: 2026-05-05
+
+This repository carries a local patch aimed at improving initial directory
+display latency in large folders, plus a system-level workaround for a COSMIC
+portal FileChooser crash observed with Firefox and Chromium.
+
+## Directory listing latency
+
+The slow path was the initial construction of `Item` values in `src/tab.rs`.
+On a test folder with about 2000 entries, raw filesystem enumeration and stat
+calls completed in a few milliseconds, while COSMIC Files took multiple seconds
+before showing the directory.
+
+The local patch keeps initial item construction cheap:
+
+- directory child counts are no longer computed synchronously in
+  `item_from_entry` and `item_from_gvfs_info`;
+- initial MIME detection uses extension-based `mime_guess`;
+- regular files use a generic file icon during the initial scan instead of
+  resolving the full MIME icon immediately.
+
+This keeps folders and `.desktop` files special-cased, while avoiding expensive
+per-file work for ordinary files during first paint.
+
+Measured locally during investigation:
+
+- before the MIME/icon changes: about 3.1 seconds for `~/Téléchargements`;
+- after avoiding full MIME icon resolution during scan: below the temporary
+  100 ms perf-log threshold for the same folder.
+
+## File chooser portal workaround
+
+Firefox and Chromium were failing to open `Save As` on the first attempt because
+`xdg-desktop-portal-cosmic` crashed while handling `FileChooser`.
+
+Logs showed:
+
+```text
+Backend call failed: Remote peer disconnected
+xdg-desktop-portal-cosmic ... status=11/SEGV
+```
+
+The working local system workaround is to remove
+`org.freedesktop.impl.portal.FileChooser` from:
+
+```text
+/usr/share/xdg-desktop-portal/portals/cosmic.portal
+```
+
+so the file chooser falls back to GTK. The resulting local `cosmic.portal`
+keeps COSMIC for the other interfaces:
+
+```ini
+[portal]
+DBusName=org.freedesktop.impl.portal.desktop.cosmic
+Interfaces=org.freedesktop.impl.portal.Access;org.freedesktop.impl.portal.Screenshot;org.freedesktop.impl.portal.Settings;org.freedesktop.impl.portal.ScreenCast
+UseIn=COSMIC
+```
+
+Backups created locally:
+
+```text
+/usr/share/xdg-desktop-portal/portals/cosmic.portal.bak-codex-20260505-filechooser
+/usr/share/xdg-desktop-portal/cosmic-portals.conf.bak-codex-20260505
+/usr/share/xdg-desktop-portal/cosmic-portals.conf.bak-codex-20260505-2
+```
+
+After editing portal files, restart:
+
+```sh
+systemctl --user restart xdg-desktop-portal.service xdg-desktop-portal-gtk.service
+```
+
+Package updates may overwrite `/usr/share/xdg-desktop-portal/portals/cosmic.portal`.
+If `Save As` starts needing two attempts again, re-check that `FileChooser` has
+not been reintroduced in `cosmic.portal`.