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

packaging/native/smoke-test.sh

@@ -52,17 +52,17 @@ echo "== installed: $PKG"
 # before check_dependencies() touches GTK, so it proves the wrapper, the
 # PYTHONPATH layout and the entry module's import chain — the dependency
 # typelibs are exercised by the import smoke below.
-vocalinux --version
-vocalinux-gui --version
+voculinux --version
+voculinux-gui --version
 
 # Import smoke in the shape of the AUR gate: the app modules, the vendored
 # pywhispercpp wheel, and the distro gi/GTK typelibs, all through the same
 # interpreter and environment the launcher sets up. pynput is only checked
 # for presence: its __init__ selects a display backend and raises ImportError
 # with no DISPLAY, which is why the app guards it with PYNPUT_AVAILABLE.
-PYTHONPATH="/usr/lib/vocalinux/app:/usr/lib/vocalinux/vendor" \
+PYTHONPATH="/usr/lib/voculinux/app:/usr/lib/voculinux/vendor" \
 PYTHONNOUSERSITE=1 \
-LD_LIBRARY_PATH="/usr/lib/vocalinux/vendor/pywhispercpp.libs" \
+LD_LIBRARY_PATH="/usr/lib/voculinux/vendor/pywhispercpp.libs" \
 /usr/bin/python3 - <<'PY'
 import importlib
 import importlib.util
@@ -83,11 +83,11 @@ for module in MODULES:
     importlib.import_module(module)
 
 spec = importlib.util.find_spec("pynput")
-assert spec and spec.origin and spec.origin.startswith("/usr/lib/vocalinux/vendor/"), \
+assert spec and spec.origin and spec.origin.startswith("/usr/lib/voculinux/vendor/"), \
     f"vendored pynput not found on sys.path: {spec}"
 
 tag = f"cpython-{sys.version_info.major}{sys.version_info.minor}-"
-exts = [p.name for p in Path("/usr/lib/vocalinux/vendor").glob("_pywhispercpp.*.so")]
+exts = [p.name for p in Path("/usr/lib/voculinux/vendor").glob("_pywhispercpp.*.so")]
 assert any(tag in name for name in exts), \
     f"no _pywhispercpp extension for {tag[:-1]} among {exts}"