fix(tests): eliminate env mutex poison cascade (#1558)

* fix(tests): eliminate env mutex poison cascade and fix test flakiness

The shared ENV_MUTEX used by ~68 config tests would cascade a single
test panic into failures across every module. Replace all .unwrap() /
.expect() lock acquisitions with a poison-recovering lock_env() helper.
Consolidate rogue module-local ENV_LOCK instances (workspace, orchestrator,
bootstrap) onto the shared global mutex to prevent cross-module races.

Also fixes:
- gateway user_id fallback was hardcoded to "default" instead of owner_id
- test_ironclaw_env_path used LazyLock which is order-dependent

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* test(helpers): add regression test for lock_env poison recovery

Satisfies the regression-test-check CI gate by adding a test that
intentionally poisons ENV_MUTEX and verifies lock_env() recovers.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix(ci): detect test changes inside #[cfg(test)] regions

The regression test check relied on git diff -W to expand context to
function boundaries, but git doesn't recognize Rust `mod tests {}` as a
function boundary. Changes to imports, helpers, or lock calls inside
test modules were invisible to the check.

Add a line-level fallback: for each changed .rs file, find where
#[cfg(test)] starts and check if any diff hunk targets a line at or
after that boundary. This catches edits anywhere inside test modules
regardless of git's language awareness.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* fix: address PR review feedback

- Clear ENV_MUTEX poison after regression test so it doesn't leave
  global state dirty for subsequent tests.
- Fix CI regression-test-check to match #[cfg(test)] only when followed
  by `mod` (the test module pattern), avoiding false positives from
  standalone #[cfg(test)] items like statics or functions.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

.github/workflows/regression-test-check.yml

@@ -121,6 +121,7 @@ jobs:
           fi
 
           # Whole-function context: detect edits inside existing test functions.
+          # Uses -W (whole function) which works when git recognises function boundaries.
           if git diff "${BASE_REF}...${HEAD_REF}" -W -- '*.rs' | awk '
             /^@@/           { if (has_test && has_add) { found=1; exit } has_test=0; has_add=0 }
             /^ .*#\[test\]/ || /^ .*#\[tokio::test\]/ || /^ .*#\[cfg\(test\)\]/ || /^ .*mod tests/ { has_test=1 }
@@ -132,6 +133,40 @@ jobs:
             exit 0
           fi
 
+          # Line-level check: detect changes inside #[cfg(test)] mod blocks.
+          # git -W relies on function boundary detection which misses Rust mod blocks,
+          # so this fallback checks whether changed line numbers fall within test modules.
+          # We specifically match #[cfg(test)] that is followed by `mod` (same or next
+          # line) to avoid false positives from standalone #[cfg(test)] items like
+          # individual statics or functions.
+          CHANGED_RS=$(echo "$CHANGED_FILES" | grep '\.rs$' || true)
+          if [ -n "$CHANGED_RS" ]; then
+            while IFS= read -r rs_file; do
+              [ -f "$rs_file" ] || continue
+
+              # Find the line where #[cfg(test)] precedes a `mod` declaration.
+              # Handles both `#[cfg(test)] mod tests` (same line) and the two-line form.
+              TEST_MOD_START=$(awk '
+                /^[[:space:]]*#\[cfg\(test\)\].*mod / { print NR; exit }
+                /^[[:space:]]*#\[cfg\(test\)\][[:space:]]*$/ { pending=NR; next }
+                pending && /^[[:space:]]*mod / { print pending; exit }
+                { pending=0 }
+              ' "$rs_file")
+              [ -n "$TEST_MOD_START" ] || continue
+
+              # Get changed line numbers in this file from the diff hunk headers.
+              # Each @@ line looks like: @@ -old,count +new,count @@
+              while IFS= read -r hunk_line; do
+                line_no=$(echo "$hunk_line" | sed -E 's/^@@ -[0-9,]+ \+([0-9]+).*/\1/')
+                [ -n "$line_no" ] || continue
+                if [ "$line_no" -ge "$TEST_MOD_START" ]; then
+                  echo "Test changes found: $rs_file has changes at line $line_no inside #[cfg(test)] mod block (starts at line $TEST_MOD_START)."
+                  exit 0
+                fi
+              done < <(git diff "${BASE_REF}...${HEAD_REF}" -U0 -- "$rs_file" | grep -E '^@@')
+            done <<< "$CHANGED_RS"
+          fi
+
           if grep -qE '^tests/' <<< "$CHANGED_FILES"; then
             echo "Test file changes found under tests/."
             exit 0