feat(P2): Daydreamer background consolidation, community detection, and P2P sharing

[Copilot]

Implements all P2 milestone tasks: cooperative background memory consolidation (Daydreamer), label-propagation community detection with quota enforcement, and privacy-safe P2P curiosity/sharing infrastructure.

MetadataStore interface extensions

• getAllVolumes(), getAllShelves() — needed by FullNeighborRecalc and PrototypeRecomputer to enumerate hierarchy
• deleteEdge(from, to) — required for Hebbian pruning
• core/crypto/uuid.ts — randomUUID() with crypto.randomUUID() + fallback

Daydreamer modules (daydreamer/)

• IdleScheduler — cooperative task loop via requestIdleCallback / setImmediate; priority queue, FIFO tie-break, error-isolated per task
• HebbianUpdater — LTP (strengthenEdges), LTD+pruning (decayAndPrune); enforces maxDegree; triggers batchComputeSalience + runPromotionSweep for changed nodes
• FullNeighborRecalc — pairwise cosine recalc for dirty volumes; pair budget bounded by computeCapacity(graphMass) per idle cycle (O(√(t log t))); clears dirty flag, recomputes salience
• PrototypeRecomputer — volume medoid selection (minimises avg pairwise distance) and centroid, then shelf routing prototypes; appends to VectorStore; runs tier-quota sweep
• ClusterStability — deterministic label propagation on MetroidNeighbor graph; persists communityId → PageActivity; exports detectOversizedCommunities / detectEmptyCommunities

Sharing modules (sharing/)

• types.ts — CuriosityProbe (with required mimeType + modelUrn fields), GraphFragment, SubgraphSlice, EligibilityDecision
• EligibilityClassifier — regex-based PII/credential detection (credentials, credit card, IBAN, SSN, email, medical); deterministic with typed reason codes; classifyPage / filterEligible
• SubgraphExporter — BFS expansion from seed nodes, eligibility filter, creator identity stripped, provenance tagged; exportForProbe + exportForExchange
• SubgraphImporter — schema validation, sender identity stripping, safe page+edge import; importFragment / importSlice
• CuriosityBroadcaster — rate-limited probe queue; dispatches incoming graph_fragment responses to registered handler
• PeerExchange — opt-in signed subgraph exchange; inject any P2PTransport implementation

// Curiosity broadcast flow
broadcaster.enqueueProbe({ m1, partialMetroid, queryContextB64, knowledgeBoundary, mimeType, modelUrn, timestamp });
await broadcaster.flush(Date.now()); // rate-limited; sends one probe per call

// Import received fragment — identity-stripped, schema-validated
const result = await importFragment(fragment, { metadataStore, vectorStore });
// result: { nodesImported, edgesImported, rejected }

Tests

93 new tests across 8 test files (tests/daydreamer/, tests/sharing/, tests/integration/Daydreamer.test.ts). Integration test validates Williams Bound invariant (resident count ≤ H(t)) holds after multiple Daydreamer passes.

Original prompt

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This section details on the original issue you should resolve

<issue_title>P2</issue_title>
<issue_description>All P2 tasks, issues and sub issues belong here, either directly or by reference. Please subtask every issue with P2 in its name for ease of tracking.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes P2 #70

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[Copilot]

Pull request overview

Implements major Daydreamer background-maintenance modules and introduces a first pass at privacy-safe P2P sharing (curiosity probes + subgraph exchange), along with required MetadataStore API extensions and comprehensive Vitest coverage.

Changes:

• Add Daydreamer modules: idle scheduling, Hebbian edge updates, full neighbor-graph recalculation, prototype recomputation, and community detection via label propagation.
• Add sharing modules: eligibility classification, curiosity probe broadcasting, subgraph export/import, and peer exchange; centralize sharing schema in sharing/types.ts.
• Extend MetadataStore with volume/shelf enumeration and single-edge deletion; update IndexedDB backend and tests accordingly.

Reviewed changes

Copilot reviewed 26 out of 26 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
TODO.md	Marks P2 Daydreamer + sharing tasks as completed.
PLAN.md	Updates implementation status tables/exit criteria for Daydreamer + sharing.
core/types.ts	Extends MetadataStore with getAllVolumes, getAllShelves, and deleteEdge.
storage/IndexedDbMetadataStore.ts	Implements getAllVolumes, getAllShelves, and deleteEdge for IndexedDB backend.
core/crypto/uuid.ts	Adds randomUUID() helper with platform + fallback implementations.
daydreamer/IdleScheduler.ts	Adds cooperative idle-time scheduler with priority queue.
daydreamer/HebbianUpdater.ts	Adds LTP/LTD/pruning and triggers salience recompute + promotion sweep.
daydreamer/FullNeighborRecalc.ts	Adds dirty-volume full neighbor recomputation bounded by a budget.
daydreamer/PrototypeRecomputer.ts	Adds recomputation of volume/shelf prototypes and attempts to update hotpath.
daydreamer/ClusterStability.ts	Adds label propagation community detection + helper detectors.
sharing/types.ts	Introduces canonical types for probes, fragments, slices, and transport messages.
sharing/EligibilityClassifier.ts	Adds deterministic eligibility rules to block PII/credentials/etc.
sharing/SubgraphExporter.ts	Exports eligibility-filtered slices using BFS expansion.
sharing/SubgraphImporter.ts	Imports fragments/slices with schema validation + identity stripping.
sharing/PeerExchange.ts	Adds opt-in proactive slice exchange over transport.
sharing/CuriosityBroadcaster.ts	Adds rate-limited probe queue + fragment handler dispatch.
tests/sharing/*.test.ts	Adds tests for eligibility, broadcaster, and subgraph exchange round-trip.
tests/daydreamer/*.test.ts	Adds tests for idle scheduler, Hebbian updater, full recalc, prototypes, and cluster stability.
tests/integration/Daydreamer.test.ts	Adds integration coverage for Daydreamer passes using fake-indexeddb.
tests/SalienceEngine.test.ts	Updates MetadataStore mock to satisfy new interface methods.