fix(hooks): point update-graph.sh fallback build path at dist/cli.js

[carlos-alm]

Summary

• .claude/hooks/update-graph.sh's fallback build path (used when the codegraph binary isn't on PATH) invoked node .../src/cli.js, a file that has never existed in this repo — the CLI entry point is TypeScript at src/cli.ts, compiled to dist/cli.js (see package.json's bin.codegraph).
• Because stderr is redirected to /dev/null, the branch failed silently and BUILD_OK stayed 0, so the graph never rebuilt after edits for contributors without a global codegraph install.
• Fixed by pointing the fallback at dist/cli.js. Added a regression test (tests/unit/hook-fallback-build-path.test.ts) that fails if src/cli.js is ever reintroduced or if the fallback drifts from package.json's bin.codegraph entry.

Filed #1979 for an out-of-scope finding: the identical broken-fallback-path bug also exists in .claude/hooks/post-git-ops.sh.

Closes #1836

Test plan

• npx vitest run tests/unit/hook-fallback-build-path.test.ts tests/unit/hook-extensions.test.ts — both pass
• npm run lint (via biome check) on the new test file — clean
• codegraph diff-impact --staged -T — no function-level impact (shell script + test file only)

Stacked on #1833 (base branch fix/issue-1833-exports-dead-export-analysis-never-counts) — only this issue's hook fix is in the diff.

[greptile-apps]

Greptile Summary

This PR fixes the update-graph hook fallback path. The main changes are:

• update-graph.sh now invokes the compiled dist/cli.js entry point.
• A regression test checks that the hook no longer references src/cli.js.
• The test ties the fallback path to package.json's bin.codegraph entry.

Confidence Score: 5/5

This looks safe to merge after considering the fallback build-state edge case.

• The changed path matches the package CLI entry point.
• The only issue found is limited to checkouts where the compiled dist output is missing when the hook runs.

.claude/hooks/update-graph.sh

Important Files Changed

Filename	Overview
.claude/hooks/update-graph.sh	Changes the fallback CLI invocation from the nonexistent source JS path to the compiled CLI path.
tests/unit/hook-fallback-build-path.test.ts	Adds tests that guard the hook fallback path against drifting away from the package bin entry.

_{Reviews (1): Last reviewed commit: "fix(hooks): point update-graph.sh fallba..." | Re-trigger Greptile}

[greptile-apps]

Fallback Requires Built Dist

When this hook runs in a checkout where codegraph is not on PATH and dist/cli.js has not been built yet, the fallback still exits through the silent failure path because dist/ is ignored and only created after the build step. That leaves BUILD_OK at 0, so the graph rebuild is skipped without any visible error.