feat: extend physical compilation coverage for deployment computation

[zzylol]

Stacked on #491.

Rebuilt into the linear stack on main. New integrate: commit(s) fold in integration-branch resolutions this PR needs on top of the earlier stack: "let coverage lowering chains use per-node helper indices".

Why

ASAPQuery-backend still lowers and evaluates much of its computation itself. It rebuilds PromQL operators from query text (query_time.rs, physical_values.rs), computes current-series readouts in its store, and assembles value graphs by hand. In the agreed layering, the Planner physical compile (physical_planner::compile) owns all computation. The backend owns ingestion, storage, readout I/O, external exact engines, and scheduling.

What

• Inventory: docs/develop_docs/physical-compile-coverage.md maps 31 backend computation sites to Planner payloads and marks their status at feat: compile Planner selections into physical DAG candidates #475: 11 supported, 4 partial, 14 missing, 2 backend-owned.
• ReadPopulation Sum / Count / Average / Quantile now compile to grouped aggregation. A new exact Reduction::Quantile uses PromQL interpolation and puts NaN first. Global readouts of an empty population return an empty vector.
• Query-time Binary over logical value rows:
  • A scalar-literal operand is folded into a projection. This covers x * 2, 100 - x, and -x.
  • Two grouped vectors are matched one-to-one on their label columns (inner equi-join), then the operator is applied.
  • Comparisons and per-series rows fail at compile time instead of guessing.
• Exact count finalization converts Int64 to the declared Float64 value. Before, compile rejected it.

After this PR the inventory reads 17 supported, 4 partial, 8 missing, 2 backend-owned.

Before / After

Each case below goes PromQL → Planner selection → compile_post_asap_dag → compile, with raw scans as the only inputs:

Query	Before this PR	After this PR
sum by (job) (m) (maintained population)	native population readout does not support this operation	{api: 10, db: 5}
quantile by (job) (0.25, m)	same error	{api: 1.5, db: 5}
sum by (job) (sum_over_time(m[5m])) * 2	node 3: native Planner binding currently requires a unary operation	{api: 28, db: 10}
sum by (job) (sum_over_time(a[5m])) / sum by (job) (sum_over_time(b[5m]))	vector binary requires Float64 scalars or complete label-map vectors	{api: 3, db: +Inf} (unmatched groups dropped)
sum by (job) (count_over_time(m[5m]))	node 2: native output type differs from Planner output	{api: 4, db: 1}

These cases are the tests in crates/asap-physical-operators/tests/deployment_computation.rs. Each test was confirmed to fail on the base branch.

Remaining

The coverage doc lists the rest in priority order:

• lowering PromQL-shaped Fallback subtrees: range functions over matrices, scalar(), histogram_quantile, subquery grids
• comparison filters and bool comparisons (needs return_bool in Binary)
• per-series vector matching with a name-free identity
• constant-weight and EntityIdentity precompute updates
• label-map sketch-state readout
• summary join, subtract, and delete

Validation

• cargo fmt --all --check: clean
• cargo clippy --workspace --all-targets -- -D warnings: clean
• cargo test --workspace --no-fail-fast: 1363 passed, 0 failed. dag_export::workload_node_ids_make_smaller_topk_reuse_explicit does not exist on this base.
• A separate review agent, not the implementer, read the diff. It found the empty-population and NaN-ordering issues, and both are fixed in 05d0ecb. No human has reviewed this yet.

🤖 Generated with Claude Code

[zzylol]

Included in the squash merge of #487 into main (80a691c).