docs: fix PRD consistency and align all docs with SSH client-only (FR-006)

PRD fixes:
- Remove duplicate 'Installation Behavior' section
- Fix malformed terminology table (missing pipe separator)

Documentation alignment with FR-006:
- README.md: Change SSH/firewall to client-only, no inbound access
- TEST-COVERAGE.md: Remove 'Firewall allows SSH inbound'
- VERIFICATION-REPORT.md: Fix password config docs to match preseed.cfg
- COMPLIANCE.md: Change 'SSH Hardening' to 'SSH Client-Only'

Test enhancements:
- Expand unit tests for encryption, firewall, security hardening
- Add comprehensive coverage for FR-001 through FR-009 requirements

All changes ensure documentation and tests align with PRD.md FR-006
which requires SSH client-only with no server or inbound access.

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Assisted-by: GLM-4.7 via Crush <crush@charm.land>

README.md

@@ -104,8 +104,8 @@ Build KNEL-Football secure ISO with Docker-only workflow following AGENTS.md req
 - Debian Testing base
 - IceWM + LightDM desktop
 - WiFi/Bluetooth permanently disabled
-- SSH with wireguard keys
-- Firewall rules (inbound SSH, outbound VPN only)
+- SSH client-only (no server, no inbound access)
+- Firewall rules (all inbound denied, outbound VPN only)
 - USB automount support
 - QR code import for WireGuard