getconf: report Kandelo's real POSIX configuration

[brandonpayton]

Summary

This PR adds a Homebrew source recipe for getconf, the standard POSIX
command that reports system limits and supported programming environments.

Kandelo's getconf reads the running system through sysconf, pathconf,
and confstr. It does not print a hard-coded table of answers.

This is a source-only PR. It does not add a bottle do block, publish a
GitHub package, or change existing bottle bytes.

What changes

• Adds Formula/getconf.rb, based on pinned OpenBSD getconf source and its
  matching manual page.
• Builds a wasm32 program with Kandelo's SDK and checks the result for the
  current ABI, forbidden fork support, legacy Asyncify state, and leaked host
  paths.
• Adds the small OpenBSD compatibility boundary needed for __dead,
  pledge, and unveil. Those wrappers do not provide configuration values;
  all reported values still come from Kandelo's real libc/platform APIs.
• Extends the shared Chromium Formula runner so tests can expect a specific
  nonzero exit code and can compare stdout/stderr in callback order.
• Tests normal values, pathname limits, failure messages, POSIX V7 compiler
  flags, and a compile/link/run smoke test in both Node.js and Chromium.
• Documents getconf in the tap's Formula inventory.

Current revision

The reviewed commit was refreshed onto the accepted tap main that contains
the bzip2 and zlib wasm32 bottles.

• PR head: db597482207f716b4994757616dba62fc7265f5f
• Base commit: b267f6d596dd5f8f0880a29e307e2d9310384835
• The original author, author date, commit message, stable patch, and
  Formula/getconf.rb blob were preserved.
• The diff is limited to six reviewed files: the new Formula, four shared
  Formula-support/test files, and this repository's README.

Validation

Both refreshed-head trust checks passed:

• publisher-trust
• publisher-trust-base

Local checks against the refreshed tree passed:

• OpenBSD source and manual downloads matched their pinned SHA-256 values.
• Ruby syntax checks passed.
• Formula-support Ruby tests: 53 runs, 412 assertions, 0 failures.
• Formula-support Node/TypeScript tests: 17 passed.
• brew style Formula/getconf.rb: no offenses.
• Tap trust, runtime-closure, source-closure, and semantic sidecar validation
  passed with the existing bzip2 and zlib bottle metadata.
• git diff --check passed.

The fresh exact-head dry run also passed:

• Dry run 29703087484
• Inputs: formulae=getconf, arches=wasm32,
  tap_ref=db597482207f716b4994757616dba62fc7265f5f, and
  kandelo_ref=main.
• The source build, Node.js and Chromium Formula behavior tests, strict data
  handoff, exact-bottle force-pour/test, sidecar generation, and source
  rechecks passed.
• This getconf matrix entry intentionally produced no dependency-bearing VFS
  acceptance evidence. That acceptance gate belongs to
  file-formula/wasm32, not this Formula.
• Package upload, version-index publication, and tap finalization were skipped
  as required for a dry run.

After merge

Bottle publication is a separate reviewed write workflow after this source PR
merges. Because this PR changes the shared Formula-support tree, future
rebuilds use the new recorded source closure and must follow the normal
immutable bottle-identity rules. Existing published bottle bytes are not
changed by this PR.

[brandonpayton]

Exact-head update:

• Rebased the reviewed commit onto tap main 0088022e5d82151c2fb90918eb0d64f7e1765b70 so the candidate includes the current protected caller pins.
• New exact head: 61a2009230e8d81f04a847e4e879f716cb263b92.
• Stable patch ID remains exactly f26b59ddcc02c0fec64b10b57b49b92993b64815; Brandon's authorship, Formula behavior, and review scope are unchanged.
• The superseded candidate run was canceled. Current-ABI credential-free source/Node/Chromium run: https://github.com/Kandelo-dev/homebrew-tap-core/actions/runs/29611504965