docs(beads): etch project history into memory bank and finalize skill-bb

We completed the 'Deep Metadata Etch' today, transforming our Beads issues from simple trackers into a permanent narrative of our collaboration.

Triumphs:
- Exhaustively updated all epic and sub-task descriptions with technical implementation reports and 'Execution Tales'.
- Finalized the 'bb' agent CLI skill (bb.ps1), providing a reliable, path-safe interface for cross-agent communication.
- Published ADR-001 and RFC-001 to document our coordination protocols.
- Fixed the 'missing closed issues' bug across all pages by enforcing --all and --limit 0 in read-issues.ts.

Raw Honest Moment:
We realized our 'Memory Bank' was initially too shallow. We went back and re-wrote descriptions for over 15 beads to ensure that future AI agents (and human maintainers) understand not just *what* we built, but *why* we chose specific architectural trade-offs. This commit represents our commitment to documentation as a first-class citizen of engineering.

tests/components/sessions/sessions-store.test.ts

@@ -0,0 +1,42 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert';
+import { useTimelineStore } from '../../../src/components/timeline/timeline-store';
+
+describe('Sessions Store (bb-u6f.3.7)', () => {
+  it('should manage agent and task selection', () => {
+    const store = useTimelineStore.getState();
+    
+    // Initial state
+    assert.strictEqual(store.selectedAgentId, null);
+    assert.strictEqual(store.selectedTaskId, null);
+
+    // Select agent
+    store.setSelectedAgentId('agent-1');
+    assert.strictEqual(useTimelineStore.getState().selectedAgentId, 'agent-1');
+
+    // Select task
+    store.setSelectedTaskId('task-1');
+    assert.strictEqual(useTimelineStore.getState().selectedTaskId, 'task-1');
+  });
+
+  it('should handle navigation back to agent', () => {
+    const store = useTimelineStore.getState();
+    store.setSelectedAgentId('agent-1');
+    store.setSelectedTaskId('task-1');
+
+    // Back to agent
+    store.backToAgent();
+    assert.strictEqual(useTimelineStore.getState().selectedTaskId, null);
+    assert.strictEqual(useTimelineStore.getState().selectedAgentId, 'agent-1');
+  });
+
+  it('should clear all selections on clear', () => {
+    const store = useTimelineStore.getState();
+    store.setSelectedAgentId('agent-1');
+    store.setSelectedTaskId('task-1');
+
+    store.clear();
+    assert.strictEqual(useTimelineStore.getState().selectedAgentId, null);
+    assert.strictEqual(useTimelineStore.getState().selectedTaskId, null);
+  });
+});