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>

config/preseed.cfg

@@ -95,7 +95,7 @@ d-i partman/confirm boolean true
 d-i partman/confirm_nooverwrite boolean true
 
 # Package selection
-tasksel tasksel/first multiselect standard, ssh-server
+tasksel tasksel/first multiselect standard
 d-i pkgsel/include string \
     icewm \
     lightdm \
@@ -105,7 +105,7 @@ d-i pkgsel/include string \
     mousepad \
     zbar-tools \
     nftables \
-    openssh-server \
+    openssh-client \
     cryptsetup \
     cryptsetup-initramfs \
     busybox \