ci(chapel): mark chapel-build + zig-ffi non-blocking until #133 fix lands (#134)

## Summary

Adds `continue-on-error: true` to two jobs in
`.github/workflows/chapel-ci.yml` that have never passed in repository
history:

- **`chapel-build`** — `.chpl` sources use non-Chapel syntax (`extern
\"C\" { ... }`, octal escapes); see #133 for full diagnostic + fix
options.
- **`zig-ffi`** — pinned Zig 0.13.0 lacks `addLibrary` on the `Build`
namespace called by `src/zig_ffi/build.zig:23`.

Pattern follows Job 4 (`rust-chapel-real`) which already carries
`continue-on-error: true` with the same rationale (Chapel L2.2–L2.7
gated).

## Effect

- Jobs still RUN — visibility preserved (logs available for #133
debugging).
- Jobs no longer FAIL the workflow — unrelated PRs stop being
noise-blocked by the long-standing Chapel/Zig syntax issues.
- Downstream `rust-chapel-feature` (which `needs: zig-ffi`) will be
SKIPPED when `zig-ffi` fails — acceptable since the Chapel feature path
is not currently load-bearing.

## Sequencing

1. Land this PR → Chapel CI stops poisoning the signal.
2. Address #133 (Chapel rewrite + Zig API update) — substantive work.
3. Revert this PR (drop `continue-on-error`) once #133's rehabilitation
lands.

Refs #133

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/chapel-ci.yml

@@ -28,10 +28,15 @@ concurrency:
 permissions: read-all
 
 jobs:
-  # Job 1: Compile Chapel .chpl files into a shared library
+  # Job 1: Compile Chapel .chpl files into a shared library.
+  # Marked continue-on-error: true pending #133 — the .chpl sources use
+  # non-Chapel FFI syntax (`extern "C" { ... }` blocks, octal escapes)
+  # that have never compiled. Job runs for visibility but doesn't fail
+  # the workflow. Re-enable strict gating once #133's rewrite lands.
   chapel-build:
     name: Compile Chapel Metalayer
     runs-on: ubuntu-latest
+    continue-on-error: true
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
@@ -65,10 +70,16 @@ jobs:
           name: chapel-lib
           path: src/chapel/libechidna_chapel*
 
-  # Job 2: Build and test Zig FFI bridge (always uses stubs)
+  # Job 2: Build and test Zig FFI bridge (always uses stubs).
+  # Marked continue-on-error: true alongside chapel-build (#133) — the
+  # Zig 0.13.0 toolchain pinned here is missing `addLibrary` on the
+  # `Build` namespace that `src/zig_ffi/build.zig:23` calls. Either bump
+  # to the Zig that ships `addLibrary` or migrate to the supported API;
+  # tracked as part of #133's Chapel + FFI rehabilitation arc.
   zig-ffi:
     name: Build & Test Zig FFI Bridge
     runs-on: ubuntu-latest
+    continue-on-error: true
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2