feat(reconciliation): implement deterministic state reconciliation engine and post-commit hook

- Implement ReconciliationEngine in server/src/handlers/reconciliation.rs
- Auto-transition ADRs to implemented, resolve tech debts, and cascade task unblocking
- Ingest git commit events via POST /api/git/commit and scripts/git-reconcile.py post-commit hook
- Add universal pagination, search filtering, and keyboard navigation to dashboard
- Implement non-destructive task TTL expiry sweeper and gate verification
- Implements: ADR-0102, ADR-0103

server/src/handlers/tasks.rs

@@ -192,6 +192,10 @@ impl McpTool for TasksHandler {
                         session_id: None,
                         ..Default::default()
                     });
+                    if target_status == "completed" {
+                        crate::handlers::reconciliation::cascade_unblock_tasks(&state);
+                        crate::handlers::reconciliation::recalculate_milestones(&state);
+                    }
                     Ok("Task status updated.".to_string())
                 } else {
                     Err(crate::error::AppError::Internal(
@@ -452,11 +456,13 @@ impl McpTool for MilestonesHandler {
                             .as_deref()
                             .and_then(|s| s.parse::<u64>().ok()),
                         description: req.description,
+                        task_ids: req.task_ids.unwrap_or_default(),
                         deliverables: req.deliverables.unwrap_or_default(),
                         repo_name: req.repo_name,
                         ..Default::default()
                     })
                 });
+                crate::handlers::reconciliation::recalculate_milestones(&state);
                 Ok("Milestone added".to_string())
             }
             MilestoneAction::Update => {
@@ -471,12 +477,21 @@ impl McpTool for MilestonesHandler {
                     for m in ms.iter_mut() {
                         if m.id == id {
                             m.status = status.clone();
+                            if status.eq_ignore_ascii_case("completed") || status.eq_ignore_ascii_case("done") {
+                                if m.completed_at.is_none() {
+                                    m.completed_at = Some(crate::handlers::utils::now_secs());
+                                }
+                            }
+                            if let Some(task_ids) = &req.task_ids {
+                                m.task_ids = task_ids.clone();
+                            }
                             found = true;
                             break;
                         }
                     }
                 });
                 if found {
+                    crate::handlers::reconciliation::recalculate_milestones(&state);
                     Ok("Milestone updated".to_string())
                 } else {
                     Err(crate::error::AppError::Internal(