release v0.9.9: install.sh needs no sudo + CVE metadata drift fix

install.sh never escalates to sudo. The installer defaulted to
/usr/local/bin and fell back to `sudo mv`, prompting for a password on
exactly the unprivileged accounts a privilege-escalation tool targets. It
now uses /usr/local/bin only when already writable and otherwise installs
to a per-user $HOME/.local/bin (honoring XDG_BIN_HOME), no sudo ever. An
explicit SKELETONKEY_PREFIX is honored and errors rather than escalating.
The documented one-liner prepends ~/.local/bin to PATH so it resolves on a
fresh login, and the quickstart drops the misleading sudo from --scan /
--audit / --auto.

CVE metadata drift (the failing weekly drift-check):
  - CVE-2022-0492 (cgroup_release_agent) entered CISA KEV 2026-06-02;
    corpus now 13 of 36 modules cover KEV-listed CVEs.
  - CVE-2026-46333 (ptrace_pidfd) gained CWE-269 from NVD (was unclassified
    at module-add time).
Refreshed CVE_METADATA.json, generated cve_metadata.c, and KEV_CROSSREF.md;
README + website KEV counts and version bumped to 0.9.9.

core/cve_metadata.c

@@ -121,8 +121,8 @@ const struct cve_metadata cve_metadata_table[] = {
         .cwe                 = "CWE-287",
         .attack_technique    = "T1611",
         .attack_subtechnique = NULL,
-        .in_kev              = false,
-        .kev_date_added      = "",
+        .in_kev              = true,
+        .kev_date_added      = "2026-06-02",
     },
     {
         .cve                 = "CVE-2022-0847",
@@ -286,7 +286,7 @@ const struct cve_metadata cve_metadata_table[] = {
     },
     {
         .cve                 = "CVE-2026-46333",
-        .cwe                 = NULL,
+        .cwe                 = "CWE-269",
         .attack_technique    = "T1068",
         .attack_subtechnique = NULL,
         .in_kev              = false,