[P2][DATA-03] Dependency graph, invalidation and deletion

Programme: #1
Epic: #17

## Objective
Track which displayed facts, rankings, synthesized text, approvals and notifications depend on which source observations so change/deletion propagates correctly.

## Scope
- Dependency edges from observations → claims → derived entities/views/rankings/articles/approvals/alerts.
- Source tombstones, revision history and freshness policies.
- Incremental invalidation/recomputation queue.
- Different update semantics by artifact type: live field refresh, recompute ranking, propose article revision, invalidate approval.
- Deletion propagation to full-text/vector indexes, caches and future context eligibility.
- Audit of why a derivative became stale/invalid.

## Correctness rules
- Do not silently rewrite text the user is actively reading when a reviewable revision is safer.
- Material source changes invalidate pending approvals that relied on the old version.
- Tombstones/deletions must propagate without erasing immutable action receipts that are legally/operationally required.

## Acceptance criteria
- [ ] Changing a product price invalidates/recomputes affected comparison/ranking state and stale uncommitted purchase authority.
- [ ] Revoking/deleting a social post removes it from derived feeds and indexes according to policy.
- [ ] Source changes produce explainable dependency traces.
- [ ] Deleted eligible data no longer appears in search, semantic retrieval or new model context.
- [ ] Article/synthesis changes are versioned and reviewable rather than silently overwritten.
- [ ] Invalidation survives crash/restart without leaving permanent mixed revisions.

## Dependencies
- DATA-01
- CORE-02

**First phase:** P2
**Maturity target:** P5
**Owner:** workspace-ui-data

## Task issues
- [ ] #358 `DATA-03.T01` — Define dependency edges and revision semantics
- [ ] #359 `DATA-03.T02` — Record dependencies during computation
- [ ] #360 `DATA-03.T03` — Implement durable invalidation traversal
- [ ] #361 `DATA-03.T04` — Implement type-specific refresh behavior
- [ ] #362 `DATA-03.T05` — Invalidate approvals and transaction preconditions
- [ ] #363 `DATA-03.T06` — Propagate deletion through every derivative
- [ ] #364 `DATA-03.T07` — Expose invalidation explanations and audit
- [ ] #365 `DATA-03.T08` — Qualify graph convergence and recovery

This is an umbrella issue with no implementation files or entry points named. Start by reading dependencies DATA-01 and CORE-02, then work through task issues #358–#365, beginning with defining dependency edges and revision semantics. Done means the listed acceptance criteria are met, including explainable propagation, deletion handling, reviewable revisions, and crash recovery.

Written by the indexing model from the issue text.