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.

💘 Generated with Crush

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

tests/security/compliance_comprehensive_test.bats

@@ -91,7 +91,7 @@
 }
 
 @test "CIS 6.2: Audit watches /etc/sudoers" {
-    grep -q "/etc/sudoers.*-k privilege" /workspace/src/security-hardening.sh
+    grep -q "/etc/sudoers.*-k privilege_escalation" /workspace/src/security-hardening.sh
 }
 
 @test "CIS 6.2: Audit watches authentication files" {