Fix #184 transitive external repo change now reaches main-repo consumers

[tinder-maxwellelliott]

Summary

Fixes #184. The same root cause sits behind the still-open part of #197 (alias-wrap chain), so this fix benefits both shapes.

Before. BazelQueryService.queryBzlmodRepos synthesised one //external:<repo> target per bzlmod-managed repo, hashed by repo metadata only. There was no rule_input edge between those synthetic targets and no content hash of the underlying directory, so a change inside @inner never propagated to @outer or to //:consume:

//:consume    → @outer//:lib
@outer//:lib  → @inner//:data
@inner//:data → inner/data.txt

The user in #184 saw this with rules_python's pip_parse where @cryptography sits behind @moto behind a py_test rule.

After. Two changes in BazelQueryService:

1. queryBzlmodRepos now parses bazel mod graph --output=json (via BazelModService, newly injected) and, for each repo, computes the list of direct bzlmod deps. For each dep, it emits addRuleInput("//external:<dep_apparent>") on the synthetic target so RuleHasher follows the chain //:consume → //external:outer → //external:inner during digest computation.

   Module name → canonical name is bridged by stripping the trailing +<version> suffix from canonical names (works for the no-version-conflict case; skips extension-generated repos like rules_jvm_external++maven+maven because they don't appear in bazel mod graph anyway). Build.Repository.module_key is not populated by current Bazel, so we cannot key off that.

2. repositoryToTarget now content-hashes the on-disk directory of every local_repository-rule repo (which is what local_path_override lowers to) and attaches the digest as a synthetic _bazel_diff_content_hash attribute. MODULE.bazel.lock is skipped because bazel regenerates it indeterministically. BCR-fetched repos are left alone — their version is already in the metadata, so a version bump flips the synthetic target's hash via that channel.

ModuleGraphParser gains a parseModuleGraphDepEdges helper that returns module_name → [dep_module_names] from the same JSON parseModuleGraph already consumes.

The reproducer test loses its @Ignore, picks up the standard Bazel 8.6.0+ skip guard (the fix relies on mod show_repo --output=streamed_proto), and is renamed …_reproducerForIssue184 → …_regressionForIssue184.

Test plan

• Manual end-to-end on Bazel 9.1 against the bzlmod_transitive_external fixture: editing inner/data.txt with no extra flags now lists //:consume in the impacted-targets output (was empty before).
• bazel test //cli:E2ETest --test_filter=testTransitiveExternalRepoChangeImpactsConsumer_regressionForIssue184 → PASSED in 2.9s.
• Full unit-test sweep across 12 kt_jvm_test targets → all 12 PASSED.
• Broad non-Maven E2ETest sweep (testTransitiveExternalRepo*, testBzlmodLocalPathOverride*, testModuleBazelCommentOnly*, testGoModUpdate*, testMacroBzlChange*, testBzlmodShowRepoDetects*, testExcludeExternalTargets*, testFineGrainedHashBzlMod, testBzlmodTransitiveDepsQuery, testGenerateHashesWithCquery, …) → PASSED in 113.6s.

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