cleanup(codegen): remove dead Codegen fields region_stack + bump_ptr (+ orphaned RegionInfo)

[hyperpolymath]

Summary

Per typed-wasm proposal 0001 Appendix B "Producer-readiness checklist"
follow-up. Both fields in `Codegen` were marked `#[allow(dead_code)]`
with the comment "reserved for future interpreter use" — declared,
initialized in `Codegen::new()`, never read or written elsewhere in
the crate.

Removed

• `Codegen.region_stack: Vec` field + its constructor init
• `Codegen.bump_ptr: u32` field + its constructor init (adjacent dead
  code in the same struct, same "reserved" comment)
• `RegionInfo` struct (only consumer was `region_stack`; orphaned
  after removal — its own fields were already `#[allow(dead_code)]`)

Retained

• `REGION_HEADER_SIZE` constant — `pub`, conceptually describes the
  linear-memory layout (used by comments at lines 28 + 76 + within the
  wasm-side memory-layout code at ~1506-1531 that manipulates the
  wasm-memory `bump_ptr` cell at offset 0). Removing the Rust-side
  dead struct field does not affect the wasm-side memory layout.

Important disambiguation

The wasm-side `bump_ptr` (a value stored in wasm linear memory at
offset 0, real and load-bearing) is unrelated to the removed Rust
`Codegen.bump_ptr` struct field of the same name. The struct field
was a stale carry-over from an earlier design where the Codegen
tracked it Rust-side; the actual implementation tracks it inside the
emitted wasm. The naming collision is what kept the dead field
camouflaged.

Verification

• `cargo check -p ephapax-wasm` — clean, no warnings
• `cargo test -p ephapax-wasm` — 84/84 pass

Carry-forward note

This closes the dead-code item from typed-wasm proposal 0001 Appendix B.
The access-sites codegen follow-up is filed at the ephapax counterpart
to affinescript#462.

🤖 Generated with Claude Code

[github-actions]

🔍 Hypatia Security Scan

Findings: 69 issues detected

Severity	Count
🔴 Critical	7
🟠 High	16
🟡 Medium	46

⚠️ Action Required: Critical security issues found!

View findings

[
  {
    "reason": "Action perpolymath/standards/.github/workflows/governance-reusable.yml@main\n needs attention",
    "type": "unpinned_action",
    "file": "governance.yml",
    "action": "pin_sha",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in abi-verify.yml",
    "type": "missing_timeout_minutes",
    "file": "abi-verify.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in codeql.yml",
    "type": "missing_timeout_minutes",
    "file": "codeql.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in coq-build.yml",
    "type": "missing_timeout_minutes",
    "file": "coq-build.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in governance.yml",
    "type": "missing_timeout_minutes",
    "file": "governance.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in hypatia-scan.yml",
    "type": "missing_timeout_minutes",
    "file": "hypatia-scan.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in mirror.yml",
    "type": "missing_timeout_minutes",
    "file": "mirror.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in rust-ci.yml",
    "type": "missing_timeout_minutes",
    "file": "rust-ci.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in scorecard-enforcer.yml",
    "type": "missing_timeout_minutes",
    "file": "scorecard-enforcer.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  },
  {
    "reason": "Issue in scorecard-enforcer.yml",
    "type": "missing_timeout_minutes",
    "file": "scorecard-enforcer.yml",
    "action": "flag",
    "rule_module": "workflow_audit",
    "severity": "medium"
  }
]

Powered by Hypatia Neurosymbolic CI/CD Intelligence