feat(query): route carrier sum and count+sum reads through run_path_query

[QuantumExplorer]

Follow-up to #803 (merged) and #798 (merged) — the dispatch wiring both PRs left open.

What this closes

run_path_query's AggregateCarrier arm served only the count axis and refused the other two by name:

AggregateKind::Sum | AggregateKind::CountAndSum => Err(Error::NotSupported(
    "carrier aggregate-sum reads have no trusted per-key read primitive; use \
     prove_query with verify_aggregate_sum_query_per_key / ..."
))

That was accurate when #798 landed — the readers didn't exist. #803 added them, so the arm now routes all three axes:

AggregateKind	reader
Count	query_aggregate_count_per_key
Sum	query_aggregate_sum_per_key (newly reachable)
CountAndSum	query_aggregate_count_and_sum_per_key (newly reachable)

Every shape classify() can produce now has a reader behind it. The only NotSupported the dispatch still raises is the read-mode version gate, which is intentional and unrelated. Module doc updated to say so.

The result-type decision

PathQueryRun gains two variants rather than collapsing the carrier family:

AggregateCountPerKey(Vec<(Vec<u8>, u64)>),             // existed
AggregateSumPerKey(Vec<(Vec<u8>, i64)>),               // new
AggregateCountAndSumPerKey(Vec<(Vec<u8>, u64, i64)>),  // new

The plan for this follow-up was to mirror a VerifiedPathQuery::AggregatePerKey { per_key: Vec<(Vec<u8>, Option<u64>, Option<i64>)> }. That type does not exist anywhere in the repo — #798 shipped the read dispatch only, and its own module doc notes that "the unified proof dispatch arrives separately." With no mirror target, three typed variants win on every axis I can find:

• Consistent with this enum's own leaf family one screen above: AggregateCount(u64) / AggregateSum(i64) / AggregateCountAndSum { count, sum }. Collapsing only the carrier half would make the two halves disagree.
• Honest types. A sum carrier can never produce a count, so Option<u64> would be statically always-None on that axis — the collapsed shape encodes a value that can't occur.
• Additive. AggregateCountPerKey is already public on develop; collapsing it is a breaking change to a just-shipped variant.
• 1:1 with the readers, so the routing is a straight hand-off with no reshaping.

When the unified verify dispatch lands, it should mirror these three variants rather than the collapsed shape.

Tests

aggregate_carrier_count_matches_per_key_reader_and_others_are_refused existed to assert the refusal, so it is now aggregate_carrier_all_kinds_match_their_per_key_readers: a differential assertion per axis (unified answer == dedicated reader) over ProvableSumTree and PCPS carrier fixtures, plus a check of the values themselves so the test would catch both readers being wrong in the same way.

New: aggregate_carrier_per_key_dispatch_surfaces_reader_errors. Routing must not paper over a reader's rejection, so a non-tree outer match and a single-axis host under a combined carrier each have to fail through run_path_query with the same error text the dedicated reader produces.

Validation

• cargo clippy --workspace --all-features -- -D warnings — clean (exit 0, zero diagnostics)
• cargo test -p grovedb -p grovedb-query --all-features — 2633 + 255 pass, 0 fail
• cargo build --no-default-features --features verify -p grovedb — clean
• cargo fmt --check — clean

No version gating: purely additive routing over readers that are already gated on their own existing slots (query_aggregate_{sum,count_and_sum}_on_range), so no new slots and no V4 gate.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.27%. Comparing base (44a6260) to head (dbe548d).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #805   +/-   ##
========================================
  Coverage    92.27%   92.27%           
========================================
  Files          265      265           
  Lines        79920    79922    +2     
========================================
+ Hits         73750    73752    +2     
  Misses        6170     6170           

Components	Coverage Δ
grovedb-core	90.60% <100.00%> (+<0.01%)	⬆️
merk	93.13% <ø> (ø)
storage	87.00% <ø> (ø)
commitment-tree	96.05% <ø> (ø)
mmr	96.79% <ø> (ø)
bulk-append-tree	89.82% <ø> (ø)
element	97.92% <ø> (ø)

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[QuantumExplorer]

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📥 Commits

Reviewing files that changed from the base of the PR and between 44a6260 and dbe548d.

📒 Files selected for processing (2)

• grovedb/src/operations/get/run_path_query.rs
• grovedb/src/tests/run_path_query_tests.rs

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