docs(context): Main Fuel reads EPC detail; Wall/Roof/Heating filter by bucket

Updates the portfolio Property-table flagged-ambiguity note for the two changes
in the previous commit: Main Fuel now reads epc_main_heating_detail beneath the
override (no longer override-only for new-approach), and Wall/Roof/Heating are
now filterable via coarse prefix/substring buckets while still displaying the
full free-text description.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CONTEXT.md

@@ -192,7 +192,7 @@ _Avoid_: estimation notification, banner (those are component names)
 
 ## Flagged ambiguities
 
-- The portfolio **Property table**'s **Property Type**, **Built Form**, **Construction Age**, **Main Fuel**, **Wall Type**, **Roof Type** and **Heating System** columns show the **landlord-override-resolved** value — the same precedence the modelling **Run filter** applies (override fact → EPC-derived → **Unknown**) — not the raw `epc_property` value or the legacy property-row column. See [ADR-0012](./docs/adr/0012-portfolio-list-resolves-descriptors-via-override-precedence.md). The first four are also **filters**; Wall/Roof/Heating are display-only (their override vocabularies are too large for a chip filter) and read the **main building part** for the per-part ones (wall/roof). Two label subtleties: **Construction Age** is an RdSAP band (e.g. "1900–1929", "before 1900"), never a single year (it was formerly the "Year Built" column); and **Main Fuel** is override-only for new-approach properties, so it reads **Unknown** unless a landlord override supplies it.
+- The portfolio **Property table**'s **Property Type**, **Built Form**, **Construction Age**, **Main Fuel**, **Wall Type**, **Roof Type** and **Heating System** columns show the **landlord-override-resolved** value — the same precedence the modelling **Run filter** applies (override fact → EPC-derived → **Unknown**) — not the raw `epc_property` value or the legacy property-row column. See [ADR-0012](./docs/adr/0012-portfolio-list-resolves-descriptors-via-override-precedence.md). All seven are also **filters**, and the per-part ones (wall/roof) read the **main building part**. Wall/Roof/Heating filter by **coarse bucket** rather than the full vocabulary — their resolved values are free-text (override vocab / EPC `epc_energy_element.description` / legacy column) with hundreds of variants, so a fixed set of prefix/substring buckets (Wall → Cavity / Solid Brick / Timber Frame / Stone / …; Roof → Pitched / Flat / Room-in-Roof / …; Heating → Gas Boiler / Community / Electric Storage / Heat Pump / …) matches them, while the columns still **display the full description**. `classifyDescriptor` is the pure twin of the SQL bucketing. Two label subtleties: **Construction Age** is an RdSAP band (e.g. "1900–1929", "before 1900"), never a single year (it was formerly the "Year Built" column); and **Main Fuel** for new-approach properties reads the EPC's `epc_main_heating_detail.main_fuel_type` (an RdSAP `main_fuel` code or an EPR string, folded to a coarse label) beneath any landlord override — it only reads **Unknown** when neither is present.
 - The UI surfaces labelled **"Current EPC"** and **"Current Efficiency State"** (property table, building-passport card) show **Effective performance**, not Lodged — despite the glossary advising against "current performance" for Effective. The label is a product choice ("current" = the property's true present-day modelled state); the underlying datum is still **Effective performance**. The **"Lodged EPC"** column/badge is the only surface showing **Lodged performance**, and only when a real certificate exists (`source = lodged`).
 - "Upload" is used in the codebase to mean both the file-on-S3 and the BulkUpload row. We standardise on **BulkUpload** for the row; the file is just "the source file."
 - "Onboarding" appears in some route paths (`bulk_onboarding_inputs/...`) but isn't part of this glossary — we use **BulkUpload** end-to-end.