fix(rest): execute search-style GET bundle entries as searches

[angela-helios]

Closes #478

The bug

Bundle GET entries were unconditionally parsed as Type/id reads. GET Patient?name=Nguyen became a read of resource type Patient?name=Nguyen — a 404 in batch bundles, and a 400 rejecting the whole bundle in transactions — even though the spec's processing rules allow any read or search URL in a GET entry (this is what blocked the #476 screenshot bundle and got the bug filed).

The fix

• parse_request_url strips the query string before extracting type/id, so scope checks and reads see the real resource type.
• A GET entry addressing a type (Patient?name=x, or bare Patient) now runs through the same search pipeline as the HTTP endpoint (execute_search_bundle, factored out of the search handler): terminology expansion, _list/chain resolution, _include, paging clamps. The resulting searchset Bundle is embedded as the entry's resource with 200 OK. Instance reads (Patient/123) are untouched.
• Transactions: the spec orders GETs after all writes, and a search cannot run inside the storage transaction, so search entries execute against the just-committed state — which also makes them see the bundle's own writes (tested: POST a patient + GET Patient?family=Tran in one transaction finds it). Their queries are validated up front, so a malformed search still rejects the whole bundle before anything executes; a post-commit execution failure surfaces as that entry's own error outcome rather than a misleading whole-bundle failure for writes that did commit. GET-by-id keeps running inside the storage transaction as before.

Tests

New search_entries conformance tests: batch search entry returns a searchset, bare-type GET is a search, batch mixing read + search entries, transaction search seeing the bundle's own writes, transaction GET-by-id unchanged. Full helios-rest suite green (33 test binaries, incl. batch_conformance 44, search_integration 101, rest_conformance 84); clippy clean.

[codecov]

Codecov Report

❌ Patch coverage is 87.82609% with 14 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/rest/src/handlers/batch.rs	89.13%	10 Missing ⚠️
crates/rest/src/handlers/search.rs	82.60%	4 Missing ⚠️

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