v0.3.1: --dump-offsets tool + NOTICE.md per module

The README has been claiming "each module credits the original CVE
reporter and PoC author in its NOTICE.md" since v0.1.0, but only
copy_fail_family actually shipped one. Fixed.

  modules/<name>/NOTICE.md (×19 new + 1 existing): per-module
    research credit covering CVE ID, discoverer, original advisory
    URL where public, upstream fix commit, IAMROOT's role.

  iamroot.c: new --dump-offsets subcommand. Resolves kernel offsets
    via the existing core/offsets.c four-source chain (env →
    /proc/kallsyms → /boot/System.map → embedded table), then emits
    a ready-to-paste C struct entry for kernel_table[]. Run once
    as root on a target kernel build; upstream via PR. Eliminates
    fabricating offsets — every shipped entry traces back to a
    `iamroot --dump-offsets` invocation on a real kernel.

  docs/OFFSETS.md: documents the --dump-offsets workflow.
  CVES.md: notes the NOTICE.md convention + offset dump tool.

  iamroot.c: bump IAMROOT_VERSION 0.3.0 → 0.3.1.

modules/cls_route4_cve_2022_2588/NOTICE.md

@@ -0,0 +1,25 @@
+# NOTICE — cls_route4 (CVE-2022-2588)
+
+## Vulnerability
+
+**CVE-2022-2588** — `net/sched` cls_route4 handle-zero dangling-filter
+UAF → kernel R/W via msg_msg cross-cache refill.
+
+## Research credit
+
+Discovered and disclosed by **kylebot** / **xkernel**, August 2022.
+
+Public PoC + writeup: <https://www.willsroot.io/2022/08/lpe-on-mountpoint.html>
+(William Liu's analysis built on kylebot's trigger).
+
+Upstream fix: mainline 5.20 / stable 5.19.7 (Aug 2022).
+Branch backports: 5.4.213 / 5.10.143 / 5.15.69 / 5.18.18 / 5.19.7.
+
+## IAMROOT role
+
+The module uses `unshare(USER|NET)`, brings up a dummy interface,
+creates an htb qdisc + class, adds a `route4` filter, then deletes
+it to leave the dangling pointer. msg_msg sprays kmalloc-1k while
+a UDP `classify()` walk follows the dangling pointer. `--full-chain`
+re-fires with a faked tcf_proto.ops pointer aimed at the
+modprobe_path overwrite via the shared finisher.