feat: plan 16 P2 batch 1 (SEC-13 SSRF, SEC-27 log-escape, SEC-28 path-traversal)

- SEC-13 (M-09): SSRF allowlist on provider-usage-fetch (always block non-http(s)
  schemes; enforced mode blocks internal/link-local IPs + non-allowlisted hosts,
  dev keeps loopback mocks); dashboard refuses non-loopback bind in enforced mode.
- SEC-27 (X-02): casan-log strips ESC/CSI + CR/LF (terminal-escape + fake-log-line
  injection) while keeping tab and visible text.
- SEC-28 (X-04): new path-guard.sh — realpath resolve + reject symlink/.. escapes
  outside the allowed root.

Verify: SEC-13 6/0, SEC-27 3/0, SEC-28 4/0, adversarial 44/44, run-casan4 0-FAIL.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

AINative_OKR_CASAN5/.specify/tests/phase-sec27-tests.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+set -uo pipefail
+
+# CASAN Plan-16 SEC-27 (X-02) — strip control/ANSI chars from log output.
+#
+# Log messages carry attacker-influenced data (action names, tool-output snippets).
+# A raw ESC/CSI sequence can rewrite a reviewer's terminal; a raw CR/LF can inject a
+# fake log line. casan_log now strips control chars (keeping tab). Proves the ESC
+# byte and embedded newlines are removed while the visible text survives.
+#
+# Deterministic; no model/network.
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+PASS=0; FAIL=0
+pass() { echo "PASS: $1"; PASS=$((PASS + 1)); }
+fail() { echo "FAIL: $1"; FAIL=$((FAIL + 1)); }
+
+echo "===== Plan-16 SEC-27: log control-char stripping ====="
+
+# shellcheck source=/dev/null
+source "$PROJECT_ROOT/.specify/scripts/bash/casan-log.sh"
+
+PAYLOAD="$(printf 'start\033[31mRED\033[0m\nFAKE [ERROR] injected-audit-line')"
+OUT="$(casan_log error test "$PAYLOAD" 2>&1)"
+
+if printf '%s' "$OUT" | od -An -c | grep -q '033'; then
+  fail "ESC byte survived into the log (terminal-escape injection)"
+else
+  pass "ESC byte stripped from log output"
+fi
+
+LINES="$(printf '%s\n' "$OUT" | grep -c .)"
+[[ "$LINES" -eq 1 ]] \
+  && pass "embedded newline stripped — no injected second log line" \
+  || fail "log emitted $LINES lines (newline injection)"
+
+printf '%s' "$OUT" | grep -q "start" && printf '%s' "$OUT" | grep -q "RED" \
+  && pass "visible text preserved (only control bytes removed)" \
+  || fail "visible text lost"
+
+echo ""
+echo "===== SEC-27 SUMMARY: PASS=$PASS FAIL=$FAIL ====="
+[[ "$FAIL" -eq 0 ]] || exit 1