feat: implement global workspace, working memory and the cognitive cycle

Phase 4 (ADR-0001). internal/attention scores thought candidates as a
normalised weighted sum over ten named features with a per-term
breakdown, ranked by (score, id) so ordering is total and replayable.
internal/workspace holds the capacity-limited workspace (refresh by
subject, decayed competition, explained admit/reject outcomes) and the
decaying working memory.

internal/brain runs one runtime per active mind: debounced wake-ups from
the event bus (own output never re-triggers), a settle window so
concurrently committing events are not skipped, bounded concurrent
Observe calls with per-process isolation and timeouts, deterministic
scoring, a loop detector that suppresses recurring thoughts and raises a
metacognition warning, executive dispatch by thought kind, and one
transaction per cycle whose events are published only after commit.
Every candidate, selection, attention shift and broadcast is an event
with provenance back to the triggering observation. Operators can run a
cycle, pause, resume, reset transient state and change attention
weights live; the manager reconciles runtimes with mind status.

cognition/attend is the first process: deterministic candidates from
external events using an urgency lexicon, novelty against context and
trust-based operator priority.

PLAN.md

@@ -69,13 +69,16 @@ An administrator can: start Noema → log in → create a mind → configure per
 - ☑ `noemactl event inspect|list|tail`, `noemactl observe`
 - ☑ Tests: bus bounds and filtering, append validation, immutability, filters, cursors, causal lookups, SSE end to end
 
-### Phase 4 – Working memory, global workspace, attention
-- ☐ `internal/brain`: `BrainState`, `Process` interface, registry, cycle loop, bounded pool, per-mind runtime lifecycle, modes, cursor advance, loop detector
-- ☐ `internal/attention`: feature extraction, weights, deterministic scorer, admission
-- ☐ `internal/workspace`: capacity-limited workspace + working memory with decay, persistence in `workspace_states`
-- ☐ `migrations/0004_workspace`
-- ☐ UI: workspace page (contents, candidates, scores, why won/lost), working memory panel
-- ☐ Tests: determinism, capacity, decay, cancellation, pool bounds, loop detection, restart continuity
+### Phase 4 – Working memory, global workspace, attention ☑
+- ☑ `internal/attention`: ten named features, per-mind weights, normalised weighted sum with per-term breakdown, total ordering by (score, id)
+- ☑ `internal/workspace`: capacity-limited workspace with refresh-by-subject, decayed competition, explained outcomes; working memory with activation decay and least-active eviction; token overlap for context relevance
+- ☑ `internal/brain`: `Process` interface and registry, per-mind runtime with debounced wake-ups, idle timer, settle window, cursor advance only on read events, bounded concurrent Observe with isolation and timeouts, deterministic scoring, loop detector with metacognition warning, executive dispatch by thought kind, single transaction per cycle with publish after commit, persisted snapshot, operator commands (cycle, pause, resume, reset, reload), cycle rate budget; manager reconciling active minds and waking on bus events (own output never re-triggers)
+- ☑ `internal/cognition/attend`: deterministic attention candidates from external events (urgency lexicon, novelty vs context, trust-based operator priority)
+- ☑ `migrations/0004_workspace`
+- ☑ API: workspace view, cycle now, mode, reset; config changes reload runtimes
+- ☑ UI: workspace page (contents with score breakdown bars, working memory, last cycle candidates with fate and reason, controls, attention weight editor) refreshing live on broadcasts
+- ☑ `noemactl workspace show|cycle|pause|resume|reset`
+- ☑ Tests: scoring determinism and bounds, ranking order, admission/refresh/capacity/decay/prune, provenance chain across a cycle, restart continuity, no self-triggered cycles, loop suppression, pause/reset/cancellation
 
 ### Phase 5 – Episodic and semantic memory
 - ☐ `migrations/0005_memory`: memories (kinds, tsvector), memory_relationships, memory_embeddings (conditional pgvector)