Feature: Add alias-backed Solr support for search indexing (ALT)

[mdorf]

Summary

Adds SolrCloud alias support to Goo, enabling zero-downtime full re-indexing of ontology search collections.

After migrating from static Solr XML schemas to dynamic SolrCloud, the ability to index into an alternate core and swap was lost. This PR restores that capability using SolrCloud aliases: models reference alias names, aliases point to versioned physical collections, and atomic alias swaps (CREATEALIAS) enable zero-downtime re-indexing.

Key changes

• Alias CRUD (solr_admin.rb): list_aliases, alias_exists?, resolve_alias, create_alias, delete_alias — all via SolrCloud Collections API
• Two-mode connector (solr_connector.rb): init() accepts a bootstrap_collection: parameter. When the bootstrap name differs from the alias name → aliased mode (alias + physical collection, re-index capable). When same or nil → plain collection mode (no alias, backward-compatible for collections like :ontology_metadata)
• Re-index workflow (solr_connector.rb + goo.rb):
  • create_reindex_collection(name) — creates a new collection with the correct schema
  • promote_alias(name) — atomically swaps the alias, keeps the old collection (for rollback)
  • swap_alias_and_delete_old(name) — swaps and deletes the old collection
  • Goo.create_reindex_connection, Goo.reindex_client, Goo.complete_reindex, Goo.promote_alias — module-level API
• DSL passthrough (search.rb): enable_indexing now accepts and forwards bootstrap_collection: to the connector
• Tests (test_solr.rb): Full coverage for alias-aware init, plain collection init, reindex collection creation, alias swap, promote, and cleanup

How it works

# Aliased mode (term_search, prop_search):
enable_indexing(:term_search, :main, bootstrap_collection: :term_search_bootstrap)
# First boot: creates collection "term_search_bootstrap", creates alias "term_search" → "term_search_bootstrap"
# Subsequent boots: resolves alias, uses existing collection
# Re-index: create new collection → index into it → promote alias → optionally delete old

# Plain mode (ontology_metadata):
enable_indexing(:ontology_metadata)
# Creates collection "ontology_metadata" directly, no alias

Test plan

• bundle exec ruby -Itest test/solr/test_solr.rb — alias lifecycle, reindex, promote, plain mode
• Verify existing test/test_search.rb tests still pass
• End-to-end: boot with aliased connectors, confirm alias creation in Solr Admin UI
• End-to-end: create reindex collection, index data, promote alias, verify search resolves through new collection