Records index: replace granular Format filter with Record Type (with later format sub-facet)

[holden]

Problem

The Format facet on /records currently exposes the raw record_formats.name field. This produces ~27+ visible options on the sidebar — many of which are noisy near-duplicates of each other caused by data entry drift.

Examples from production data today:

• Singles: 7-inch (13,242) — and separately Singles: 7-Inch (1), Singles: 7-inch. (1), Singles: 7-rpm (1) — all the same physical thing
• LPs: 10/12-inch (4,324) and LPs 10/12-inch (1) — same thing, missing colon
• Gold Standard Singles with "447" prefix (44) and Gold Standard Singles with '447' prefix (separate row, only the quote char differs)
• 22 record_formats are not assigned to any record_type_id (covering 4 records)

This makes the facet effectively useless for filtering — users can't tell which entries are real and which are typos, and the long tail dilutes the signal of the top buckets.

Data model recap

We have two tables:

• record_formats — 57 distinct values (granular, noisy). records.record_format_id points here.
• record_types — 5 clean values (broad, parent). record_formats.record_type_id points here.

So record_type is already modeled as the parent of record_format. We just don't surface it on the index page.

Counts across the active collection (user 1, 20,380 records) when grouped by record_type:

Type	Records
45s	14,710
LPs	4,536
Picture Sleeves	1,007
78s	123
Sound postcard	0

That's 99.98% coverage in 4 buckets vs 27+ confusing rows today.

Proposal

Two-phase rollout. Phase 1 is a quick UX win; Phase 2 unlocks deeper filtering once the data is cleaned.

Phase 1 — Replace Format facet with Type facet (this PR)

• Add has_one :record_type, through: :record_format on Record
• Replace the @formats query in RecordsController#load_filter_options with @record_types (join through record_formats, group by record_types.name, hide buckets with count = 0)
• Update the sidebar partial to render Type instead of Format
• Switch the Ransack predicate from record_format_id_in to filter by record_format_id_in derived from the selected Type (or via a new record_type_id ransacker)
• Verify existing sort options keyed on record_format_* still work (the FK stays, only the facet changes)

Phase 2 — Add Format as cascading sub-facet (separate issue/PR)

After data normalization, when a Type is selected, expose its child Formats as a second filter group:

• Backfill the 22 orphan formats with the correct record_type_id
• Merge typo variants into canonical rows (Singles: 7-Inch → Singles: 7-inch, etc.)
• Drop empty/zero-count formats
• Render Format checkboxes only when a Type is active

Wireframes

Current — single noisy Format facet

+--------------------------------+
| Format                       ^ |
+--------------------------------+
| [ ] Singles: 7-inch     13,242 |
| [ ] LPs: 10/12-inch      4,324 |
| [ ] Promotional Singles  1,149 |
| [ ] Picture Sleeves      1,002 |
| [ ] EPs: 7-inch            274 |
| [ ] Singles: 10/12-inch    135 |
| [ ] Singles: 78 rpm        121 |
| [ ] Singles: 12-inch        64 |
| [ ] Gold Standard Sing...   44 |
| [ ] Picture Disc Singles    16 |
| [ ] EPs: 7-inch 45 rpm       7 |
| [ ] EPs: 10-inch             6 |
| [ ] Gold Standard Pict...    5 |
| [ ] EPs: 12-inch             3 |
| [ ] Promotional 12-inch...   3 |
| [ ] Singles: 12-inch 33/45   2 |
| [ ] Gold Standard Sing...    2 |
| [ ] Promotional Single...    2 |
| [ ] LPs 10/12-inch           1 |   <-- typo dup of row 2
| [ ] 78 rpm Album             1 |
| [ ] Picture Sleeve           1 |   <-- singular vs plural dup
| [ ] Plastic Soundsheets...   1 |
| [ ] EPs: 7-inch 33/45        1 |
| [ ] Promotional LPs          1 |
| [ ] Albums: 78 rpm           1 |
+--------------------------------+

Phase 1 — Type only (ship now)

+--------------------------------+
| Type                         ^ |
+--------------------------------+
| [ ] 45s                 14,710 |
| [ ] LPs                  4,536 |
| [ ] Picture Sleeves      1,007 |
| [ ] 78s                    123 |
+--------------------------------+

Phase 2 — Type + cascading Format sub-facet (after cleanup)

When a Type is checked, its child formats appear indented below it:

+--------------------------------+
| Type                         ^ |
+--------------------------------+
| [x] 45s                 14,710 |
|     [ ] Singles: 7-inch 13,242 |
|     [ ] Promotional Sgl. 1,149 |
|     [ ] EPs: 7-inch        274 |
|     [ ] Picture Disc Sgl    16 |
|     [ ] Gold Std "447"      44 |
|     [ ] Gold Std "GB"        2 |
| [ ] LPs                  4,536 |
| [ ] Picture Sleeves      1,007 |
| [ ] 78s                    123 |
+--------------------------------+

(Picture Sleeves remains a top-level Type because it's a category in its own right, not a sub-format of 45s.)

Recommendation

Do Phase 1 now, ship it as its own PR. It's a small, low-risk change that immediately makes the facet useful for the 99.98% of records that have a clean type assignment.

Treat Phase 2 as gated on data cleanup. Don't expose the cascading Format sub-facet until the typo dedup + orphan backfill is done, otherwise the sub-list will reproduce the same noise problem at a smaller scale. File a separate cleanup issue for the data work and a follow-up issue for the UI.

Out of scope

• Changing the schema (we're keeping record_format_id on records)
• Changing the record detail page (Format stays visible there)
• Changing admin/edit forms