Mealie: fuzzy ingredient↔inventory matching + assumed staples (e.g. water)

[untraceablez]

Context

Recipe makeability is computed in backend/src/services/mealie_query_service.py by matching Mealie ingredient names against Pantrie inventory item names: case-insensitive exact match, then an ILIKE '%name%' substring fallback.

Problem

Real-world naming differences cause false "missing" results:

• "Corn Starch" in inventory vs "cornstarch" in a recipe → exact fails (space), and ILIKE '%cornstarch%' also fails because "cornstarch" is not a substring of "corn starch".
• Pantry staples a household always has (notably water) are reported as missing and clutter the shopping list.

Proposed behavior

1. Fuzzy matching between recipe ingredients and inventory items. Normalize before comparing — lowercase, collapse/remove whitespace and punctuation, singularize simple plurals — and apply a similarity threshold (token-set or Levenshtein/difflib.SequenceMatcher) so Corn Starch ≈ cornstarch, Tomatoes ≈ tomato, etc. Keep exact match as the highest-confidence tier.
2. Per-household assumed staples: a household-configurable allowlist of always-on-hand ingredients, treated as in-stock without an inventory row. water is seeded automatically for every household; users can add/remove entries.

Implementation notes

• Centralize normalization + matching in one helper so both makeability and the (future) availability endpoints share it.
• Guard the fuzzy threshold to avoid over-matching (e.g. "oil" matching "olive oil" may be desirable, but "corn" matching "cornstarch" may not — tune with real recipes).
• Staples storage: per-household, so a new model + migration (e.g. household_staples, or a JSON column on the household/settings) keyed by household. Seed each household with water on creation; backfill existing households in the migration.
• API: CRUD for a household's staples (list/add/remove), admin-or-member gated consistent with other household-scoped resources.
• Frontend: a small manager under Settings → Household (alongside the existing allergen/location managers) to view/add/remove staples, with water present by default.
• Staples are applied during makeability so a matching ingredient is counted in-stock and excluded from the missing list / shopping-list push.

Acceptance criteria

• Corn Starch (inventory) counts as present for a cornstarch ingredient.
• Common plural/spacing/case variants match.
• Each household starts with water in its staples; existing households are backfilled.
• Users can add/remove staples for their household via Settings, and changes affect makeability.
• A staple ingredient is treated as in-stock and never appears in "missing"/shopping-list pushes.
• Matching + staples logic is unit-tested with representative ingredient/inventory pairs, including near-misses that should NOT match.

Decisions

• Staples are per-household configurable, with water auto-included at the start. ✅ confirmed.

Enhances the (closed) Mealie integration epic #1. Tracked under epic #35. The normalized-matching helper here is reused by #34.