chore(release): 0.3.0

[stretchcloud]

Version bump + changelog for semantic memory v2 (merged in #22).

What 0.3.0 ships

• Namespace-scoped memory store (global/repo/session/agent) with automatic v1→v2 migration, lazy decay + reinforcement, scored retrieval with no-embedding fallback, pinning, eviction
• Prompt enrichment that actually reaches the model (250 ms budget, per-session ordering) with a collapsible recalled-context chip
• LLM-backed JUDGE→DISTILL→CONSOLIDATE consolidation with strict-JSON validation + concat fallback
• MemoryPanel namespace overview + Settings → Memory controls

Testing

• 1630/1630 tests green, typecheck + build clean
• Enrichment retrieval verified live against a real LanceDB store (planted memory recalled + correctly formatted block)