feat: add human map observation

[regenrek]

Why

• Give human operators a readable, live view of Planr graphs without changing agent-facing or JSON contracts.
• Make state and dependency progress easier to distinguish in terminal output.

How

• Add condensed and full diagram rendering, accessible state colors, and a change-driven map watcher.
• Render satisfied dependencies as blocks✓ in the tree and neutral then routes in the human diagram while preserving structured blocks links.
• Document the human-only boundary across README, CLI references, and apps/docs, with v1.6.0 release notes.

Tests

• cargo fmt --check
• cargo clippy --all-targets -- -D warnings
• cargo test (80 unit, 71 E2E, 3 ownership)
• pnpm docs:verify-reference (111 CLI commands, 52 MCP tools, 237 assertions)
• pnpm docs:verify-concepts (15 semantic checks)