fix(wipe): harden verify_wipe and host_info audit safety

[Avicennasis]

Summary

Fixes six confirmed correctness bugs in the NIST 800-88 wipe library (autorun/wipe-lib.sh). All were verified by real execution before fixing, and are covered by a new test.

Resolves: FR-076, FR-077, FR-078, FR-092, FR-093, FR-094, FR-098 (Redmine #48104, #48105, #48106, #48084, #48085, #48086, #48090).

verify_wipe

• Method-aware pattern (FR-077/093): overwrite methods (nwipe random → hdd/usb-flash/fallback) leave random data; the old all-zeros/0xFF check always failed on them (false negative). Overwrite types now verify the sample is not an unwritten all-0x00 block; erase types (nvme-ssd/sata-ssd + SED crypto variants) still require zeros/0xFF.
• Full-width offset (FR-076/092): RANDOM is 15 bits, so RANDOM*RANDOM (max ~1.07e9 blocks ≈ 550 GB) never sampled the tail of larger drives — a 2 TB drive sampled only ~27 %. Now combines three draws for 45 bits of range.
• Read-failure detection (FR-098): a failed dd read is no longer silently treated as a passing sample. (wipe-lib.sh already sets pipefail; the actual defect was the swallowed read in verify_wipe, not a wipe_drive dd call — wipe_drive uses nwipe.)
• od -v fix (found during testing): without it, od collapses repeated 16-byte lines to a * marker, so even a correctly all-zeroed drive never matched the pattern — the original verify would have false-negatived on zeroed drives too.
• Signature gains a dtype arg; wipe-now.sh and wipe-wizard.sh pass it through.

host_info (FR-078/094)

• Builds the host JSON via python3 json.dumps instead of raw printf. A DMI value containing a " produced invalid JSON that crashed init_audit's json.loads() and aborted audit initialization. Values are passed as argv (no code injection).

Testing

tests/test_verify_wipe.sh (new) covers host_info escaping, method-aware pattern logic, read-failure handling, and full-range offset coverage on a simulated 2 TB drive. Full suite green; shellcheck --severity=warning clean on all changed files.

Notes / out of scope

• wipe-lib.sh has 4 pre-existing SC2034 warnings (YELLOW/CYAN used by sourcing scripts; remainder/method_cmd dead vars) — not introduced here; left untouched to keep this change surgical.
• FR-075/091 (autorun0 local rc=$?) and FR-099 (shred pass count) were investigated and are not bugs — see the respective Redmine tickets for the evidence.