Add provider-neutral Meilisearch discovery

[OwenMcGirr]

Summary

• add a provider-neutral discovery catalog with PostgreSQL and Meilisearch adapters while preserving existing public routes and JSON contracts
• add deterministic 100K Meilisearch prepare/import/verify tooling with enriched symbol metadata, repository documents, resumable checkpoints, and search-only runtime configuration
• serve deterministic synthetic SVGs, including skin-tone variants, and keep symbol-request writes on PostgreSQL
• fix duplicate React discovery keys uncovered during the live browser workflow

Why

Issue #53 changed direction from a provider bake-off to a working product test. This makes the real local React/Hono discovery site usable with synthetic Meilisearch data without coupling React or route handlers to Meilisearch.

Test plan

• pnpm lint (passes with three existing React Fast Refresh warnings)
• pnpm typecheck
• pnpm test
• pnpm build
• git diff --check
• pnpm search:prepare
• pnpm search:import
• pnpm search:verify
• live Hono/Vite smoke tests for repositories, hidden records, random symbols, English and Spanish search, pagination, symbol detail, SVG skin variants, and PostgreSQL-backed symbol requests
• in-app browser test for home discovery, query-to-query navigation, repository browsing, skin selection, symbol detail, and clean console output

Verification result

The Meilisearch trial contains exactly 100,000 localization documents and 24 repository documents, exposes 22 public repositories, and reports no active indexing. The runtime key can search but receives 403 from key administration.

Follow-ups

Semantic/hybrid search, BGE-M3, Cloudflare comparison, hosted previews, and benchmark reporting remain separate work.

Closes #53