feat: add TeamPCP behavior detection rules + domain corpus fix

[sheeki03]

What

Three new command-shape rules inspired by the TeamPCP supply chain attack (March 2026), plus domain corpus expansion and hostname wiring fix.

New Rules

1. ProcMemAccess (High / Block)
Detects /proc/*/mem scraping via reader commands (cat, dd, strings, cp, grep). Wrapper-aware (sudo, env, env -S). Normalized args handle quoted paths. Excludes echo/printf (not file readers).

• MITRE: T1003.007 (OS Credential Dumping: Proc Filesystem)

2. DockerRemotePrivEsc (Critical / Block)
Compound rule: requires Docker remote daemon (-H tcp://, --host=tcp://, DOCKER_HOST=tcp://) AND privilege escalation (--privileged or host root mount -v /:/..., --mount type=bind,src=/). Case-sensitive -H (uppercase only, lowercase -h is container hostname). Handles env -S and --split-string wrappers. Skips -e/--env container env args.

• MITRE: T1611 (Escape to Host)

3. CredentialFileSweep (Medium / Warn)
Exec-only, per-segment, verb-gated. Fires when a read/archive command accesses 2+ credential paths (ssh keys, aws, docker, kube, gcloud, npm, pypi, gnupg, etc). 13 credential paths, full tier-1 coverage.

• MITRE: T1552.001 (Credentials In Files)

Infrastructure

• resolve_base_through_wrappers() — generic wrapper resolver for sudo/env/command/exec/nohup
• unwrap_env_split_string_segment() — unwraps env -S "cmd" and env --split-string="cmd" for all 3 rules
• Domain corpus: 8 verified security/AI vendor domains added to known_domains.csv
• additional_known_domains wired into hostname confusable detection

Fixtures

21 golden fixtures covering positive, negative, and edge cases:

• ProcMemAccess: cat, dd, sudo, echo-allow, status-allow, quoted
• DockerRemotePrivEsc: -H, --host=, root mount, mount-src-last, env-wrapper, -e allow, -h allow, local allow, env -S, --split-string
• CredentialFileSweep: tar, cat, single-allow, chmod-allow, sudo

Verification

• cargo fmt + clippy + test: 902 passed, 0 failed
• Manual shell testing: 19/19 cases correct
• CodeRabbit CLI review: all actionable findings fixed