rename: IAMROOT → SKELETONKEY across the entire project

Breaking change. Tool name, binary name, function/type names,
constant names, env vars, header guards, file paths, and GitHub
repo URL all rebrand IAMROOT → SKELETONKEY.

Changes:
  - All "IAMROOT" → "SKELETONKEY" (constants, env vars, enum
    values, docs, comments)
  - All "iamroot" → "skeletonkey" (functions, types, paths, CLI)
  - iamroot.c → skeletonkey.c
  - modules/*/iamroot_modules.{c,h} → modules/*/skeletonkey_modules.{c,h}
  - tools/iamroot-fleet-scan.sh → tools/skeletonkey-fleet-scan.sh
  - Binary "iamroot" → "skeletonkey"
  - GitHub URL KaraZajac/IAMROOT → KaraZajac/SKELETONKEY
  - .gitignore now expects build output named "skeletonkey"
  - /tmp/iamroot-* tmpfiles → /tmp/skeletonkey-*
  - Env vars IAMROOT_MODPROBE_PATH etc. → SKELETONKEY_*

New ASCII skeleton-key banner (horizontal key icon + ANSI Shadow
SKELETONKEY block letters) replaces the IAMROOT banner in
skeletonkey.c and README.md.

VERSION: 0.3.1 → 0.4.0 (breaking).

Build clean on Debian 6.12.86. `skeletonkey --version` → 0.4.0.
All 24 modules still register; no functional code changes — pure
rename + banner refresh.

.github/workflows/build.yml

@@ -37,22 +37,22 @@ jobs:
             make
           fi
 
-      - name: sanity — iamroot --version
-        run: ./iamroot --version
+      - name: sanity — skeletonkey --version
+        run: ./skeletonkey --version
 
-      - name: sanity — iamroot --list
-        run: ./iamroot --list
+      - name: sanity — skeletonkey --list
+        run: ./skeletonkey --list
 
-      - name: sanity — iamroot --scan (no exploit; just detect)
-        run: ./iamroot --scan --no-color || true
+      - name: sanity — skeletonkey --scan (no exploit; just detect)
+        run: ./skeletonkey --scan --no-color || true
         # exit code may be nonzero (vulnerable host = exit 2, missing
         # precond = exit 4) — that's diagnostic data, not CI failure
 
       - name: sanity — --detect-rules auditd
-        run: ./iamroot --detect-rules --format=auditd | head -50
+        run: ./skeletonkey --detect-rules --format=auditd | head -50
 
       - name: sanity — --detect-rules sigma
-        run: ./iamroot --detect-rules --format=sigma | head -50
+        run: ./skeletonkey --detect-rules --format=sigma | head -50
 
   # Static build job: ensures the project links cleanly when -static is
   # requested. Useful for deployment to minimal containers / fleet scans
@@ -75,7 +75,7 @@ jobs:
         # gate the merge on it. Migrate to musl-gcc when we want a
         # truly portable static binary.
         continue-on-error: true
-        run: make static && ls -la iamroot
+        run: make static && ls -la skeletonkey
 
   # Phase 4 followup (placeholder): kernel-VM matrix. Each entry runs
   # the binary against a VM running a specific (vulnerable or patched)