Build Mine Incidents report — Report #4

**Summary:** Build the Mine Incidents report — the fourth production report (Report 4). Replicates the corporate "BC Mines Sector Report – Incidents" (Metabase dashboard 382), with focus on Dangerous Occurrences (determination_type_code = 'DO').

**Scope:** Full stack — Bronze → Silver → Gold (fact_mine_incident, new dim_incident_category + bridge) → semantic model → report → UI / theme layer.

**Approach:** Same as Reports 2 and 3 — develop in the old workspace (mines-data-platform-fabricws-dev-1) with Git backups maintained throughout, then re-point notebooks and semantic model to the new Terraform workspace mcm-mdp-fabricws1-dev (warehouse mcm-mdp-fabwh1-dev, lakehouse mcm_mdp_lh1_dev) once data loads.

**Key work items:**
- Materialise effective_timestamp / effective_date_key in Gold (reported >24h late → use incident_timestamp), matching the corporate report's KPI logic.
- Add dim_incident_category (two-level hierarchy via parent code) — incident-type grouping pending Caroline's input; apply at semantic layer.
- Investigate row gap: ~2,639 source incidents not present in Silver (source 7,273 vs silver 4,634 at snapshot).
- Target: report ready mid-October 2026.