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/ptrace_traceme_cve_2019_13272/NOTICE.md

@@ -0,0 +1,27 @@
+# NOTICE — ptrace_traceme (CVE-2019-13272)
+
+## Vulnerability
+
+**CVE-2019-13272** — `PTRACE_TRACEME` on a parent that subsequently
+execve's a setuid binary leaves the now-elevated process traceable by
+the unprivileged child → cred escalation via ptrace shellcode inject.
+
+## Research credit
+
+Discovered by **Jann Horn** (Google Project Zero), June 2019.
+
+Project Zero issue: <https://bugs.chromium.org/p/project-zero/issues/detail?id=1903>
+Upstream fix: mainline 5.1.17 (commit `6994eefb0053`, June 2019).
+
+Branch backports: 4.4.182 / 4.9.182 / 4.14.131 / 4.19.58 / 5.0.20 / 5.1.17.
+
+## IAMROOT role
+
+Full jannh-style chain: fork → child `PTRACE_TRACEME` → child
+sleep+attach → parent `execve` setuid bin (pkexec/su/passwd
+auto-selected) → child wins stale `ptrace_link` → POKETEXT x86_64
+shellcode → root sh.
+
+x86_64-only; ARM/other archs return PRECOND_FAIL cleanly. No exotic
+preconditions — doesn't need userns. Works on default-config systems
+including locked-down environments without unprivileged_userns_clone.