Rename project: ubuntu-fido -> authforge

Renames the package and all artifacts to authforge to drop the
distro-specific prefix, since the roadmap targets Ubuntu + Debian +
KDE + eventually Fedora (option C in the design).

- deb packages: authforge, authforge-{daemon,pam,cli,gui,gnome-integration}
- binaries: authforged, authforgectl, authforge (GUI)
- D-Bus name: io.dangerousthings.AuthForge
- PAM module: pam_authforge_pending.so
- Paths: /etc/authforge/, /var/lib/authforge/, /usr/share/pam-configs/authforge
- PPA: ppa:dangerousthings/authforge

Filesystem path /home/work/VSCodeProjects/ubuntu_fido/ left as-is for
historical reference; can rename later via git mv at the dir level.

Verified: cargo build/test/clippy/fmt clean, pam builds, gui builds,
all 5 debs produced.

pam/pam_authforge_pending.c

@@ -0,0 +1,18 @@
+#define PAM_SM_AUTH
+#include <security/pam_modules.h>
+#include <security/pam_ext.h>
+#include <syslog.h>
+#include <stdio.h>
+
+PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags,
+                                    int argc, const char **argv) {
+    (void)flags; (void)argc; (void)argv;
+    pam_syslog(pamh, LOG_INFO, "authforge_pending: stub - allowing");
+    return PAM_IGNORE; /* implemented in Phase 6 */
+}
+
+PAM_EXTERN int pam_sm_setcred(pam_handle_t *pamh, int flags,
+                              int argc, const char **argv) {
+    (void)pamh; (void)flags; (void)argc; (void)argv;
+    return PAM_SUCCESS;
+}