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

pyproject.toml

@@ -5,7 +5,7 @@ requires = ["setuptools>=77"]
 build-backend = "setuptools.build_meta"
 
 [project]
-name = "vocalinux"
+name = "voculinux"
 dynamic = ["version"]
 description = "A seamless voice dictation system for Linux"
 readme = "README.md"
@@ -117,10 +117,10 @@ lint = [
 ]
 
 [project.scripts]
-vocalinux = "vocalinux.main:main"
+voculinux = "vocalinux.main:main"
 
 [project.gui-scripts]
-vocalinux-gui = "vocalinux.main:main"
+voculinux-gui = "vocalinux.main:main"
 
 [project.urls]
 Homepage = "https://github.com/VocaHQ/vocalinux"