Add ES-based metadata retrieval

[shuchenliu]

This PR resolves the Elasticsearch portion of #64.

1. Adapt retriever to use metadata stored in Elasticsearch

As metadata is now extracted by the upstream pipeline and indexed alongside the data mappings, the tier1 driver now includes logic to fetch and cache this metadata directly from Elasticsearch.

2. Generate operations from per-dataset metadata

Previously, tier1 relied on tier0’s unified metadata to derive the available operations. Now, metadata is retrieved and parsed per datasource, and the final operation set is constructed by combining these individual definitions.

[sentry]

Codecov Report

❌ Patch coverage is 28.65497% with 122 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../retriever/data_tiers/tier_1/elasticsearch/meta.py	22.31%	94 Missing ⚠️
...etriever/data_tiers/tier_1/elasticsearch/driver.py	39.13%	14 Missing ⚠️
src/retriever/data_tiers/utils.py	26.31%	14 Missing ⚠️

Files with missing lines	Coverage Δ
.../elasticsearch/constraints/attributes/attribute.py	52.17% <100.00%> (ø)
.../elasticsearch/constraints/attributes/meta_info.py	100.00% <100.00%> (ø)
...ch/constraints/attributes/ops/handle_comparison.py	75.00% <100.00%> (ø)
...csearch/constraints/attributes/ops/handle_match.py	87.80% <100.00%> (ø)
.../elasticsearch/constraints/qualifiers/qualifier.py	93.75% <100.00%> (ø)
...elasticsearch/constraints/types/attribute_types.py	100.00% <ø> (ø)
...elasticsearch/constraints/types/qualifier_types.py	100.00% <ø> (ø)
...ever/data_tiers/tier_1/elasticsearch/transpiler.py	77.16% <100.00%> (ø)
...retriever/data_tiers/tier_1/elasticsearch/types.py	94.20% <100.00%> (ø)
...etriever/data_tiers/tier_1/elasticsearch/driver.py	45.83% <39.13%> (-2.61%)	⬇️
... and 2 more

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