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/nft_fwd_dup_cve_2022_25636/NOTICE.md

@@ -0,0 +1,28 @@
+# NOTICE — nft_fwd_dup (CVE-2022-25636)
+
+## Vulnerability
+
+**CVE-2022-25636** — `nft_fwd_dup_netdev_offload` writes
+`flow->rule->action.entries[ctx->num_actions]` without bounds-checking
+against the allocated array size → heap OOB write in kmalloc-512.
+
+## Research credit
+
+Discovered and disclosed by **Aaron Adams** (NCC Group),
+February 2022.
+
+Original writeup:
+<https://research.nccgroup.com/2022/03/02/exploit-engineering-attacking-the-linux-kernel/>
+
+Upstream fix: mainline 5.17 (commit `fa54fee62954`, Feb 2022).
+Branch backports: 5.16.11 / 5.15.25 / 5.10.102 / 5.4.181.
+
+## IAMROOT role
+
+userns+netns reach. Hand-rolled nfnetlink batch: NEWTABLE →
+NEWCHAIN with `NFT_CHAIN_HW_OFFLOAD` → NEWRULE with 16 immediates
++ fwd, overruning `action.entries[1]`. msg_msg cross-cache groom
+into kmalloc-512 with `IAMROOT_FWD` tags.
+
+`--full-chain` extends with stride-seeded forged action_entry
+overwrite aimed at modprobe_path via the shared finisher.