[feat] OAI-PMH provider, harvest framework, and persistent identifiers

[St4NNi]

OAI-PMH data provider and harvest framework over the metadata registry, w3id persistent identifier minting and landing resolution, a registry timestamp index, and durable quarantine for permanently invalid sync events.

Changes

• OAI-PMH 2.0 data provider: all six verbs over the local realm's metadata registry, unauthenticated by protocol and limited to public documents, with opaque resumption cursors.
• Harvest framework: repository connector and harvest source models, a fenced idempotent harvest job on the existing job runtime, provenance keyed by namespace and canonical record id with no silent remap, and OAI-PMH as the first harvester kind.
• w3id persistent identifiers: idempotent minting job keyed by document id, mapping state, public landing resolution redirecting into the guarded RO-Crate read, and 410 tombstones for withdrawn ids.
• Mutable updated-at timestamp index over the metadata registry riding the same write batch as the record, with lazy cleanup of stale keys, backing incremental OAI listing.
• Durable quarantine for permanently invalid sync events instead of endless redelivery.
• Screened egress GET on the blob handle through the egress guard.

References

Closes #338
Relates to #442

[codecov]

Codecov Report

❌ Patch coverage is 92.07048% with 648 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.29%. Comparing base (134a850) to head (051e4ef).

Files with missing lines	Patch %	Lines
api/src/routes/pid.rs	47.09%	82 Missing ⚠️
operations/src/metadata/forward.rs	84.19%	70 Missing ⚠️
operations/src/metadata/visibility_index.rs	93.59%	67 Missing ⚠️
operations/src/jobs/harvest.rs	91.39%	52 Missing ⚠️
operations/src/sync_quarantine.rs	90.87%	51 Missing ⚠️
api/src/routes/oai.rs	96.39%	46 Missing ⚠️
operations/src/persistent_id.rs	91.48%	40 Missing ⚠️
operations/src/harvest/create_harvest_source.rs	87.73%	32 Missing ⚠️
operations/src/delete_metadata_document.rs	83.85%	26 Missing ⚠️
operations/src/jobs/persistent_id.rs	0.00%	24 Missing ⚠️
... and 20 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #454      +/-   ##
==========================================
+ Coverage   87.11%   87.29%   +0.18%     
==========================================
  Files         380      400      +20     
  Lines      247586   257468    +9882     
==========================================
+ Hits       215679   224766    +9087     
- Misses      31907    32702     +795     

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