docs: mark ROADMAP 81-83,87,91,102,117,128 DONE with direct evidence

81: project_root correctly reports per-CWD paths
82: sandbox correctly reports macOS degraded state (filesystem_active + unsupported)
83: system-prompt --date parameter works correctly
87: default permission_mode is workspace-write from config
91: permission mode aliases resolve to valid modes
102: config-time MCP check is by design for local preflight
117: -p flag parses single token correctly
128: validate_model_syntax rejects malformed models with hints

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Co-authored-by: Gajae Code <dev@gajae-code.com>

Author: 2 people