fix: restrict anchor_entity_id to trusted findings; re-vendor wardline taint golden

[tachyon-beep]

Addresses two P2 review findings.

1. Restrict anchor_entity_id to trusted findings (trust boundary)

validate_plugin_finding copied all plugin metadata through verbatim and overwrote only anchor_file_path. The host-reserved anchor_entity_id key — consumed by the cli's host_finding_anchor_id, taken verbatim as findings.entity_id and FK-enforced at insert — was not protected. A plugin-reported finding could therefore set it to override the trusted file anchor:

• a nonexistent id hard-failed the whole analyze run on the findings FK;
• an existing id silently mis-associated the finding.

Fix: strip the host-reserved anchor_entity_id at the plugin boundary (symmetric with the already host-overwritten anchor_file_path). The only legitimate producer — the host's duplicate-locator finding (clarion-48af930f2a) — builds its HostFinding directly and bypasses this path, so it is unaffected. No subcode-gate at the consumer (avoids fragile cross-crate string-coupling).

Tests:

• unit (host_validate.rs): reserved key stripped, anchor_file_path still injected, other plugin metadata preserved.
• e2e regression (analyze_hardening.rs) via a new opt-in fixture-plugin switch: a plugin emits a forged anchor_entity_id; the run completes and the finding falls back to a real anchor. Reverting the strip reproduces the exact FOREIGN KEY constraint failed run hard-fail.

2. Re-vendor the Wardline taint golden

The Layer-2 drift recheck in wardline_taint_fact_conformance_oracle reds when the sibling Wardline repo is present: the vendored golden's svc.leaky finding fingerprint (9a291cac) was stale. The committed Wardline authority advanced it to 242d8565 (via merge 808e4978 on release/consolidation-2026-06-26); only that one field differs.

Fix: re-vendor the golden byte-identical (cmp clean) and recompute the Layer-1 byte-pin GOLDEN_BLAKE3. This fixes the real drift rather than weakening the recheck to opt-in. Both sibling-present (5/5) and skip-clean (CI absent) paths pass.

Verification

Full CI floor green locally: fmt, clippy -D warnings, build, nextest (1977 passed, 2 skipped, run with WARDLINE_REPO set), doc -D warnings, deny check.

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