feat(migration): Spar_Migration property set + helpers (Track E commit 1/8)

[avrabe]

Summary

Foundation for v0.8.0 Track E (frozen-platform / mobile-application split + hypothetical-rebinding oracle, #150). First commit of 8 in the Track E roadmap; per the research in #153.

This PR is strictly the property-set surface + minimal helpers. No CLI, no MCP, no solver extension, no spar-moves crate yet — those land in commits 3-5 of the track.

What's in

• New non-standard property set Spar_Migration registered alongside Spar_Timing / Spar_Trace:
  • Frozen (aadlboolean) — marks an item as platform; immutable for hypothetical rebinding.
  • Mobile (aadlboolean) — marks an item as application; eligible for rebinding.
  • Allowed_Targets (list of reference (thread)) — restricts hypothetical rebinding destinations. Registered against thread for now; broaden to generic component once the AADL type table supports it (TODO doc-comment in source).
  • Pinned_Reason (aadlstring) — audit trail for why an item is platform.
• crates/spar-hir-def/src/migration.rs — new tiny module exposing:
  • is_frozen(&PropertyMap) -> bool
  • is_mobile(&PropertyMap) -> bool (defensive: Frozen wins when both are set; per §6.1)
  • Reads typed PropertyExpr::Boolean first, falls back to raw "true"/"false" strings.
• REQ-MIGRATION-{001,002,003} and TEST-SPAR-MIGRATION-{PROPS,HELPERS} rivet artifacts (append-only).
• Tests: 11 new unit tests in spar-hir-def. Total spar-hir-def test count: 435 passing.

What's out (deliberately deferred per the research roadmap §7)

• CLI: spar moves verify / enumerate / optimize — Track E commit 5.
• MCP server (spar.verify_move, spar.enumerate_moves) — Track E commits 9-10 (v0.9.0).
• Solver extension (hypothetical-binding overlay) — Track E commit 6.
• New spar-moves crate — Track E commit 4.
• HIR-level mobility cache as a struct field on ComponentInstance — Track E commit 2 (per §6.2 option B; today is option A — read on demand).
• Migration_Cost property — documented in §6.1 but only used by optimize mode (commit 12).
• COMPLIANCE.md close-out narrative — Track E commit 8.

Design references

• docs/designs/track-e-migration-research.md §6.1 (property-set design) and §6.2 (HIR-cache tradeoff)
• Issue Track E: Frozen-platform/mobile-application split + hypothetical-rebinding oracle #150 — acceptance criteria
• PR design: Track E research — migration / design-space oracle (#150) #153 — research baseline

Test plan

• cargo build --workspace — clean
• cargo test -p spar-hir-def — 435 passed (11 new)
• cargo clippy --workspace --all-targets -- -D warnings — clean
• cargo fmt --all -- --check — clean
• rivet validate — PASS (91 pre-existing schema-info warnings, none from new artifacts)

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 98.73418% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/spar-hir-def/src/migration.rs	98.21%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!