chore(bb.js): fix linting (#24902)

## Summary

- make the ESLint 9 flat config executable and apply the full
`yarn-project/foundation` lint contract to bb.js
- enable all 36 canonical explicit rules, including `import-x/no-cycle`,
core `require-await`, `no-console`, camelcase, no-only-tests, and the
three Aztec custom rules
- use the same canonical ESLint plugins, type-checked/import-x base
configs, and byte-identical Prettier import-order configuration
- fix all resulting bb.js lint and formatting violations, including
refactoring the backend factories to remove four dependency cycles
- run `yarn formatting` during every bb.js build before cache lookup and
from the default `ci-barretenberg` path
- make `formatting:fix` run both ESLint fixes and Prettier

## Canonical alignment

A machine comparison of bb.js and `yarn-project/foundation` reports:

- 36 explicit rules in each config
- identical values for 35 rules
- the same plugin set: import-x, jsdoc, tsdoc, no-only-tests, and
aztec-custom
- byte-identical implementations for all three Aztec custom rules
- byte-identical Prettier configuration, including import ordering

The sole rule-option difference is the project-specific ignore list for
`import-x/no-unresolved`. bb.js ignores `src/cbind/generated` and the
checked-in wasm symlinks because those targets are created later in
bootstrap; yarn-project has its own four generated/conditional-export
resolver exceptions. This is module-resolution plumbing, not a style
relaxation: the rule remains enabled at `error` everywhere.

## CI coverage

`merge-train/barretenberg` PRs select `ci-barretenberg`. That mode runs
`barretenberg/ts/bb.js/bootstrap.sh formatting` before the CRS/C++ work.
Normal bb.js builds also run the same check before a build-cache hit can
return early.

A temporary `src/lint_probe.ts` containing a disallowed `console.log`
made the exact bootstrap formatting command exit 1 with `no-console`;
removing it made the command exit 0. The lint command also passes in a
fresh worktree where the wasm symlinks are unresolved and
`src/cbind/generated` is absent.

## Testing

- machine comparison of canonical/bb.js explicit rule maps and plugin
sets
- byte comparison of canonical/bb.js Prettier configs and custom rule
implementations
- `yarn formatting`
- `yarn install --immutable`
- focused strict TypeScript compile of the refactored backend factories
and implementations
- `CI=1 AVM=0 AVM_TRANSPILER=0 barretenberg/ts/bb.js/bootstrap.sh
formatting`
- the same bootstrap command in a fresh worktree with unresolved
generated artifacts
- red/green lint probe through the bootstrap command
- exact-head `ci-barretenberg` passed
- exact-head `ci-barretenberg-full` passed bb.js formatting, binding
generation, and ESM/CommonJS/browser builds; that wider job later
stopped in the separate bb-avm-sim build because `@aztec/ipc-runtime`
was unavailable

Author: IlyasRidhuan

barretenberg/ts/bb.js/.prettierrc.json

@@ -2,5 +2,10 @@
   "singleQuote": true,
   "trailingComma": "all",
   "printWidth": 120,
-  "arrowParens": "avoid"
+  "arrowParens": "avoid",
+  "importOrder": ["^@aztec/(.*)$", "<THIRD_PARTY_MODULES>", "^\\./|\\.\\./"],
+  "importOrderSeparation": true,
+  "importOrderSortSpecifiers": true,
+  "importOrderParserPlugins": ["importAssertions", "typescript", "decorators", "explicitResourceManagement"],
+  "plugins": ["@trivago/prettier-plugin-sort-imports"]
 }

barretenberg/ts/bb.js/bootstrap.sh

@@ -12,10 +12,21 @@ hash=$(hash_str \
   $(semver check $REF_NAME && echo 1 || echo 0) \
   ${AVM_TRANSPILER:-1})
 
-function build {
-  echo_header "bb.js build"
+function prepare_project {
   (cd .. && ./bootstrap.sh generate_bb_avm_sim_package)
   (cd .. && npm_install_deps)
+}
+
+function formatting {
+  echo_header "bb.js formatting"
+  prepare_project
+  yarn formatting
+}
+
+function build {
+  echo_header "bb.js build"
+  prepare_project
+  yarn formatting
 
   if ! cache_download bb.js-$hash.tar.gz; then
     find . -exec touch -d "@0" {} + 2>/dev/null || true

barretenberg/ts/bb.js/eslint-rules/no-async-dispose.js

@@ -0,0 +1,61 @@
+// @ts-check
+
+/**
+ * @fileoverview Rule to disallow async [Symbol.dispose]() methods.
+ * Use [Symbol.asyncDispose]() with AsyncDisposable instead.
+ */
+
+/** @type {import('eslint').Rule.RuleModule} */
+export default {
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Disallow async [Symbol.dispose]() methods',
+      category: 'Best Practices',
+      recommended: true,
+    },
+    messages: {
+      asyncDispose: '[Symbol.dispose]() should not be async. Use [Symbol.asyncDispose]() with AsyncDisposable instead.',
+    },
+    schema: [],
+  },
+
+  create(context) {
+    return {
+      MethodDefinition(node) {
+        // Match computed property keys like [Symbol.dispose]
+        if (!node.computed || !node.key || node.key.type !== 'MemberExpression') {
+          return;
+        }
+
+        const key = node.key;
+        if (
+          key.object.type !== 'Identifier' ||
+          key.object.name !== 'Symbol' ||
+          key.property.type !== 'Identifier' ||
+          key.property.name !== 'dispose'
+        ) {
+          return;
+        }
+
+        // Check if the method is async
+        if (node.value.async) {
+          context.report({ node, messageId: 'asyncDispose' });
+          return;
+        }
+
+        // Check if the return type annotation contains Promise
+        // @ts-expect-error returnType is a typescript-eslint AST extension
+        const returnType = node.value.returnType?.typeAnnotation;
+        if (
+          returnType &&
+          returnType.type === 'TSTypeReference' &&
+          returnType.typeName?.type === 'Identifier' &&
+          returnType.typeName.name === 'Promise'
+        ) {
+          context.report({ node, messageId: 'asyncDispose' });
+        }
+      },
+    };
+  },
+};