feat: v0.2 sovereign change planning

[aidankhogg]

Motivation

• Introduce a deterministic, provider-neutral change-planning layer (v0.2) that sits between static world declarations and any future runtime/provider execution.
• Prevent early provider-driven architecture choices by evaluating proposals offline, admitting or rejecting them, and producing non-executable reconciliation plans.

Description

• Add src/netsovereign/planning.py implementing canonical JSON/digests, accepted revision lineage, typed Change objects, observed-state snapshots, compare_worlds, admit_change, and build_plan producing provider-neutral ReconciliationPlan and approval gates.
• Extend the CLI (src/netsovereign/cli.py) with diff, admit, and plan commands, offline observed snapshot loading, and stable JSON output for decisions and plans.
• Expand documentation (docs/roadmap.md, README.md, CHANGELOG.md) to describe the v0.2 acceptance boundary and roadmap through v1.0.
• Bump package API/version to 0.2.0 and export planning types from the package root.
• Add tests (tests/test_planning.py) that exercise digest determinism, separation of provider-bindings from canonical intent, mandate-aware admission rules, observed drift handling, deterministic plan construction, and CLI end-to-end flows.

Testing

• Ran linters and static checks: uv run ruff check src tests (passed).
• Type checks: uv run mypy (passed).
• Unit test suite: uv run pytest (29 tests passed).
• Build produced distributions: uv build (wheel and sdist built successfully).
• New tests specifically exercise canonical_json/digest, compare_worlds, admit_change, build_plan, observed snapshot handling, and the diff/admit/plan CLI commands (all passing).

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[chatgpt-codex-connector]

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