PMM-15028 Flatten dashboards/, move pmm-app into the ui/ monorepo

[fabio-silva]

Ticket number: PMM-15028

Feature build: SUBMODULES-0

Summary

Developer-experience restructuring requested in PMM-15028:

• Flatten dashboards/: dashboards/dashboards/* is moved up to dashboards/*, so the top-level dashboards/ folder holds only JSON dashboard definitions (plus misc/ tooling and LICENSE/README.md, kept for the RPM spec's %license/%doc lines — see caveats below).
• Move pmm-app into the ui/ monorepo: dashboards/pmm-app → ui/apps/pmm-app, now a Yarn workspace + Turborepo member alongside pmm and pmm-compat. The plugin id (pmm-app) and its dist layout are unchanged, so no downstream Grafana paths change.
• Symlink preserved: src/dashboards is recreated at its new location, retargeted to the flattened top-level dashboards/ folder. plugin.json's 68 dashboard includes paths resolve unchanged — verified against the new symlink target.
• No manual reload needed: added a chokidar-based watcher (ui/apps/pmm-app/scripts/watch-dashboards.mjs) that mirrors dashboard JSON edits into the provisioned dashboards directory during local dev; wired into pmm-app's dev script (concurrently alongside the existing webpack watcher) and into .devcontainer/Makefile's run-ui/build-ui targets. QAN JS/TS changes already auto-reload via the existing webpack + livereload setup, just relocated.
• Fixed pmm-app's lint/test scripts to be non-mutating/one-shot (previously lint ran eslint --fix and test ran jest --watch), matching pmm-compat's conventions — required for these to behave correctly once folded into the shared workspace pipeline.
• Updated AGENTS.md guides (root, dashboards/, ui/, ui/apps/pmm-app/) and CONTRIBUTING.md docs to match the new layout.

Explicitly out of scope / required follow-up

This PR intentionally does not touch CI workflows or packaging, since those need a real CI run / RPM build to validate safely (not feasible in the sandbox this draft was authored in):

• .github/workflows/dashboards.yml and .github/workflows/ui.yml still reference the old paths (dashboards/dashboards/*.json, dashboards/pmm-app/...) and need updating — the dashboards.yml build/test jobs become redundant once pmm-app is a ui/ workspace member, and the "verify plugin.json paths" check should move to ui.yml.
• build/packages/rpm/server/SPECS/percona-dashboards.spec (make -C dashboards release, cp -a ./dashboards/pmm-app/dist ...) hard-depends on the pre-move paths and needs updating to build ui/apps/pmm-app via turbo — this is the highest-risk gap, since no GitHub Actions check builds RPMs, so a missed update wouldn't be caught by CI.
• .github/CODEOWNERS should get an explicit /ui/apps/pmm-app/ entry so review routing for QAN isn't silently absorbed by the generic /ui/ rule.

This PR should not be merged to a release-affecting branch until that follow-up lands. Opening as a draft for that reason, and to get early feedback on the restructuring approach itself.

Verification done

• readlink -f ui/apps/pmm-app/src/dashboards resolves to the repo-root dashboards/ folder.

• Verified all 68 plugin.json include paths resolve through the new symlink (no missing files).

• Attempted yarn install at ui/ to reconcile pmm-app's dependencies into the shared workspace lockfile — blocked in this sandbox by an organization egress policy denying codeload.github.com (a pre-existing transitive git dependency of @grafana/ui, already present in pmm-app's own lockfile before this change, unrelated to the restructuring). Needs to be run in CI or a real dev environment before merge to confirm dependency hoisting resolves cleanly (pmm-app currently pins older react/typescript/@grafana/eslint-config versions than the rest of ui/).

• Grepped the repo for stale dashboards/dashboards/ or dashboards/pmm-app/ references outside the explicitly deferred CI/RPM files — none found.

• API Docs updated — N/A, no API changes.

Links to related work items: PMM-15028

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Generated by Claude Code

[fabio-silva]

Closing in favor of #5720, opened from a renamed branch (pmm-15028-draft-l6b9se) with the commit history rewritten to drop Claude authorship/co-authorship.

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Generated by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.64%. Comparing base (31318c7) to head (c5031d9).
⚠️ Report is 81 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5719      +/-   ##
==========================================
+ Coverage   43.59%   44.64%   +1.04%     
==========================================
  Files         415      418       +3     
  Lines       43134    43329     +195     
==========================================
+ Hits        18804    19343     +539     
+ Misses      22454    22076     -378     
- Partials     1876     1910      +34     

Flag	Coverage Δ
admin	34.96% <ø> (+0.17%)	⬆️
agent	47.92% <ø> (-1.12%)	⬇️
managed	44.98% <ø> (+1.99%)	⬆️
vmproxy	72.22% <ø> (ø)

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