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

docs/INSTALL_MANUAL.md

@@ -12,7 +12,7 @@ Related: [DISTRO_COMPATIBILITY.md](DISTRO_COMPATIBILITY.md), [TROUBLESHOOTING.md
 
 ## System packages by distribution
 
-Install desktop/system dependencies **before** creating a venv or running `pip install vocalinux`. Pip cannot install GTK typelibs, AppIndicator, PortAudio, or text-injection tools.
+Install desktop/system dependencies **before** creating a venv or running `pip install voculinux`. Pip cannot install GTK typelibs, AppIndicator, PortAudio, or text-injection tools.
 
 Debian 11 and earlier are unsupported; the Debian instructions start at Debian
 12, which is the oldest release with the required Python 3.11.
@@ -84,7 +84,7 @@ sudo dnf install -y \
 
 ### Arch Linux
 
-Prefer the AUR package (`yay -S vocalinux`). Manual packages:
+Prefer the AUR package (`yay -S voculinux`). Manual packages:
 
 ```bash
 sudo pacman -S --needed \
@@ -125,7 +125,7 @@ Gentoo, Alpine, Void, Solus, Mageia: [DISTRO_COMPATIBILITY.md](DISTRO_COMPATIBIL
 Use the **system** Python (`/usr/bin/python3`). Distro PyGObject (`gi`) is compiled for that interpreter only, so a venv from pyenv/conda/uv cannot import it even with `--system-site-packages`.
 
 ```bash
-cd vocalinux
+cd voculinux
 /usr/bin/python3 -m venv venv --system-site-packages
 source venv/bin/activate
 pip install --upgrade pip setuptools wheel
@@ -141,14 +141,14 @@ pip install -e ".[dev,vad]"   # development
 ### Desktop integration
 
 ```bash
-mkdir -p ~/.config/vocalinux \
-         ~/.local/share/vocalinux/models \
+mkdir -p ~/.config/voculinux \
+         ~/.local/share/voculinux/models \
          ~/.local/share/applications \
          ~/.local/share/icons/hicolor/scalable/apps
 
-cp vocalinux.desktop ~/.local/share/applications/
-VENV_PATH=$(realpath venv/bin/vocalinux)
-sed -i "s|^Exec=vocalinux|Exec=$VENV_PATH|" ~/.local/share/applications/vocalinux.desktop
+cp voculinux.desktop ~/.local/share/applications/
+VENV_PATH=$(realpath venv/bin/voculinux)
+sed -i "s|^Exec=voculinux|Exec=$VENV_PATH|" ~/.local/share/applications/voculinux.desktop
 
 cp resources/icons/scalable/*.svg ~/.local/share/icons/hicolor/scalable/apps/
 gtk-update-icon-cache -f -t ~/.local/share/icons/hicolor
@@ -159,14 +159,14 @@ gtk-update-icon-cache -f -t ~/.local/share/icons/hicolor
 Same system packages as above, then:
 
 ```bash
-python3 -m venv ~/.local/share/vocalinux-pypi/venv --system-site-packages
-source ~/.local/share/vocalinux-pypi/venv/bin/activate
+python3 -m venv ~/.local/share/voculinux-pypi/venv --system-site-packages
+source ~/.local/share/voculinux-pypi/venv/bin/activate
 pip install --upgrade pip setuptools wheel
-pip install vocalinux
-# vosk engine: pip install "vocalinux[vosk]"
-# faster-whisper: pip install "vocalinux[faster_whisper]"
-# parakeet engine: pip install "vocalinux[parakeet]"
-vocalinux
+pip install voculinux
+# vosk engine: pip install "voculinux[vosk]"
+# faster-whisper: pip install "voculinux[faster_whisper]"
+# parakeet engine: pip install "voculinux[parakeet]"
+voculinux
 ```
 
 `--system-site-packages` lets the venv use distro GTK bindings (`python3-gi`). Building PyGObject from pip is often painful on Ubuntu/Debian.
@@ -177,18 +177,18 @@ If the app starts but no speech model is present, open Settings and download a m
 
 ```bash
 # After system packages are installed:
-pipx install vocalinux
-vocalinux
+pipx install voculinux
+voculinux
 ```
 
 pipx still cannot install system desktop libraries. Install those first with your package manager.
 
 ## Why system packages are required
 
-Vocalinux uses GTK3, AppIndicator/Ayatana, PortAudio, and tools such as `xdotool`, `wtype`, and clipboard utilities. Those come from the distro. PyPI only supplies Python packages and wheels.
+Voculinux uses GTK3, AppIndicator/Ayatana, PortAudio, and tools such as `xdotool`, `wtype`, and clipboard utilities. Those come from the distro. PyPI only supplies Python packages and wheels.
 
 ## After install
 
-- Run: [INSTALL.md](INSTALL.md#running-vocalinux)
+- Run: [INSTALL.md](INSTALL.md#running-voculinux)
 - Engines and models: [USER_GUIDE.md](USER_GUIDE.md)
 - Failures: [TROUBLESHOOTING.md](TROUBLESHOOTING.md)