Feature: metrics

After merging master, #8309's perf wins target functions that either no
longer exist (wrapExecute / wrapFields / pathToArray / finishResolvers
moved out of instrumentations/graphql.js) or live in a deleted file
(resolve.js was folded into execute.js). Port the still-applicable
changes onto the migrated execute plugin:

  #1 _startResolveSpan uses info.fieldNodes[0] instead of .find(fn =>
     fn.kind === 'Field'). The executor only hands FieldNode siblings.
  #2 pathToArray switches to count-then-fill (drops the trailing
     .reverse() and the push-grow).
  #3 getResolverInfo lazy-allocates resolverVars: skips both the
     up-front {} and the directive-loop assignment when args is empty
     and no directives have arguments.
  #4 shouldInstrument early-returns on config.depth < 0 (no-limit, the
     default-enabled case) before walking the path.
  #5 buildCollapsedPathString builds the collapsed key in one walk;
     drops the intermediate collapsedPath array. iastResolveCh.publish
     now passes raw path / pathString, matching the contract the old
     resolve.js had with the IAST subscriber.
  drive-by  wrapFields iterates Object.values(type._fields) directly.

  #7 (addVariableTags early-return) already auto-merged during the
     master merge.
  #6 (single documentSources.get in wrapExecute) is already the shape
     of bindStart in the migrated plugin.

The reverted depth=0 bindStart short-circuit (156a557 / ca2d041)
sat at a different position — inside bindStart, gated on _depthDisabled
(config.depth === 0). It was rolled back because piling it on top of
the resolveAsync depth-flag fix didn't move plugin-graphql-long-with-
depth-off any further. This port stays inside shouldInstrument, fires
on config.depth < 0 (the *enabled* default), and targets the hot path
on plugin-graphql-long.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

After merging master, #8309's perf wins target functions that either no
longer exist (wrapExecute / wrapFields / pathToArray / finishResolvers
moved out of instrumentations/graphql.js) or live in a deleted file
(resolve.js was folded into execute.js). Port the still-applicable
changes onto the migrated execute plugin:

  #1 _startResolveSpan uses info.fieldNodes[0] instead of .find(fn =>
     fn.kind === 'Field'). The executor only hands FieldNode siblings.
  #2 pathToArray switches to count-then-fill (drops the trailing
     .reverse() and the push-grow).
  #3 getResolverInfo lazy-allocates resolverVars: skips both the
     up-front {} and the directive-loop assignment when args is empty
     and no directives have arguments.
  #4 shouldInstrument early-returns on config.depth < 0 (no-limit, the
     default-enabled case) before walking the path.
  #5 buildCollapsedPathString builds the collapsed key in one walk;
     drops the intermediate collapsedPath array. iastResolveCh.publish
     now passes raw path / pathString, matching the contract the old
     resolve.js had with the IAST subscriber.
  drive-by  wrapFields iterates Object.values(type._fields) directly.

  #7 (addVariableTags early-return) already auto-merged during the
     master merge.
  #6 (single documentSources.get in wrapExecute) is already the shape
     of bindStart in the migrated plugin.

The reverted depth=0 bindStart short-circuit (156a557 / ca2d041)
sat at a different position — inside bindStart, gated on _depthDisabled
(config.depth === 0). It was rolled back because piling it on top of
the resolveAsync depth-flag fix didn't move plugin-graphql-long-with-
depth-off any further. This port stays inside shouldInstrument, fires
on config.depth < 0 (the *enabled* default), and targets the hot path
on plugin-graphql-long.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>