feat(identity): rename user-visible identity to voculinux with one-time legacy import

The fork takes its own name everywhere a user can see it: binaries
(voculinux, voculinux-gui), desktop entry, autostart, tray, D-Bus
namespace (com.voculinux.Voculinux, no alias for the old name),
config/data/cache dirs, single-instance lock, IBus engine identity,
tray icons, resource prefixes, VOCULINUX_* environment names, and the
update-checker user agent. The internal Python module stays vocalinux
and the distribution metadata keeps the upstream URLs as provenance.

On first run a previous Vocalinux install's config.json, custom
dictionary, and portal restore token are copied once into the new
locations (new config always wins, no merge, no write-back); models
re-resolve through the pinned-checksum download path. An offline
naming-sweep test proves no old-name strings remain on user-visible
surfaces outside the allowlist.

Refs #18

tests/test_native_packaging.py

@@ -26,7 +26,7 @@ RELEASE_YML = WORKFLOWS / "release.yml"
 PIPELINE_YML = WORKFLOWS / "unified-pipeline.yml"
 
 #: Runtime dependencies no distro packages; build.sh vendors their wheels
-#: under /usr/lib/vocalinux/vendor instead of declaring distro deps.
+#: under /usr/lib/voculinux/vendor instead of declaring distro deps.
 VENDORED = ("pywhispercpp", "pynput")
 
 #: pip name -> the Debian/Ubuntu package that Provides it. pywhispercpp's own
@@ -267,9 +267,9 @@ def test_nfpm_contents_and_launcher_env_agree() -> None:
     text = BUILD_SH.read_text(encoding="utf-8")
     smoke = SMOKE_SH.read_text(encoding="utf-8")
     for where in (text, smoke):
-        assert "/usr/lib/vocalinux/app" in where
-        assert "/usr/lib/vocalinux/vendor" in where
-    assert "/usr/bin/vocalinux" in text and "/usr/bin/vocalinux-gui" in text
+        assert "/usr/lib/voculinux/app" in where
+        assert "/usr/lib/voculinux/vendor" in where
+    assert "/usr/bin/voculinux" in text and "/usr/bin/voculinux-gui" in text
     assert "pywhispercpp.libs" in text and "pywhispercpp.libs" in smoke
     # Arguments keep their boundaries: $* into an unquoted exec re-splits a
     # path like "Meeting notes.wav" before argparse sees it (PR #913).
@@ -286,8 +286,8 @@ def test_smoke_gate_covers_both_formats() -> None:
     smoke = SMOKE_SH.read_text(encoding="utf-8")
     assert "debian|ubuntu)" in smoke, "smoke must install the .deb on Debian-family images"
     assert "fedora)" in smoke, "smoke must install the .rpm on Fedora"
-    assert "vocalinux --version" in smoke
-    assert "vocalinux-gui --version" in smoke
+    assert "voculinux --version" in smoke
+    assert "voculinux-gui --version" in smoke
     assert "pywhispercpp.model" in smoke, "the smoke must prove the vendored extension loads"
     assert (
         'find_spec("pynput")' in smoke