fix: Add isDevBuild() util and namespace mock node dir per instance

[charlesvien]

1. Add isDevBuild() utility to env.ts to separate dev/prod feature gates from ASAR packaging checks
2. Replace !app.isPackaged dev/prod checks across with isDevBuild()
3. Namespace the mock node symlink dir per instance (/tmp/agent-node-dev vs /tmp/agent-node-prod) to avoid cross-contamination between simultaneous dev and prod builds
4. Leave app.isPackaged in place for the 4 sites that genuinely need ASAR .unpacked path resolution

[charlesvien]

• fix: Fix sidebar project switching, stale notifications and auto-scroll #1182 : 2 dependent PRs (#1183 , #1184 )
• fix: Add isDevBuild() util and namespace mock node dir per instance #1177 👈 (View in Graphite)
• feat: Add repository mismatch warning on folder select #1181
• main

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[graphite-app]

Merge activity

• Mar 11, 11:54 AM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.
• Mar 11, 12:21 PM UTC: Graphite couldn't merge this PR because it failed for an unknown reason (GitHub is reporting that this PR is not mergeable, despite passing required status checks defined by your branch protection rules. Please check your rulesets for additional blocking criteria. Graphite Merge Queue does not currently support rulesets. Please contact Graphite support for further assistance.).