fix(ui): restore resource-row expand chevron to leading edge (closes #1006)

[cristim]

Summary

• The expand/collapse chevron on multi-variant Opportunities rows was rendering inline inside the content cell (before the Resource Type text) for readonly/viewer sessions, because buildListMarkup omitted the leading td.checkbox-col when showCheckboxes was false.
• Owner decision (issue ux(opportunities): confirm expand-chevron position (moved to front of Resource Type) #1006): chevron belongs at the far-left edge, before the Provider column, for all roles.
• This PR restores consistent placement by always emitting a leading td.checkbox-col and th.checkbox-col regardless of role, with the chevron inside it for cell summary rows and an empty cell for variant/header rows.

Changes

• frontend/src/recommendations.ts: remove the showCheckboxes condition from chevronCell (cell summary rows); drop inlineChevron inline-injection; always emit <th class="checkbox-col"> in the header (empty for viewers); always emit <td class="checkbox-col"> in variant rows (empty for viewers); update zero-rows empty-hint colspan to always include 1 for the leading column.
• frontend/src/__tests__/recommendations-permissions.test.ts: update readonly grouped-row test to assert chevron lives in td.checkbox-col; update SP-group variant-row test to expect one empty td.checkbox-col per row (no input[data-rec-id]).

Test plan

• npm run typecheck passes
• npm run build passes (pre-existing entrypoint-size warning only)
• npx jest --no-coverage src/__tests__/recommendations.test.ts src/__tests__/recommendations-permissions.test.ts - 422 tests, 0 failures
• Verify in browser: as a readonly user, the expand chevron on Opportunities rows appears at the far-left edge (before Provider), not inline before Resource Type text

Closes #1006

Summary by CodeRabbit

• Bug Fixes
  • Improved table alignment in read-only recommendation views by consistently preserving the leading column.
  • Ensured expand/collapse controls remain clearly positioned in grouped summary rows.
  • Prevented selection checkboxes from appearing in read-only sessions.
  • Corrected empty-state row alignment when no recommendations match.

[cristim]

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b8e6a7c7-04f1-42cd-8c7a-85d339d8cbef

📥 Commits

Reviewing files that changed from the base of the PR and between e43b989 and 21aad04.

📒 Files selected for processing (1)

• frontend/src/__tests__/recommendations-permissions.test.ts

📝 Walkthrough

Walkthrough

Readonly recommendations tables now preserve the leading checkbox column for structural alignment, place expand chevrons within it, and keep checkbox inputs disabled by omission. Empty-state colspan calculations and permission tests were updated accordingly.

Changes

Readonly recommendations alignment

Layer / File(s)	Summary
Render aligned readonly columns frontend/src/recommendations.ts	Readonly variant rows and headers retain empty checkbox-col cells, grouped-row chevrons render in that column, and empty states include the leading column in their colspan.
Validate readonly DOM structure frontend/src/__tests__/recommendations-permissions.test.ts	Permission tests verify header and row alignment, chevron placement, and the absence of readonly checkbox inputs.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• LeanerCloud/CUDly#798: Establishes chevron placement within the recommendations table’s leading checkbox column.
• LeanerCloud/CUDly#807: Introduces related grouped parent/child rendering and readonly checkbox gating.
• LeanerCloud/CUDly#876: Updates recommendations viewer rendering and checkbox-column permission behavior.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes restoring the expand chevron position and references the linked issue.
Linked Issues check	✅ Passed	The changes restore the chevron to the far-left column and keep alignment consistent across roles, matching #1006.
Out of Scope Changes check	✅ Passed	The diff stays focused on chevron placement, table alignment, and related tests with no unrelated feature work.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/1006-chevron-leading-edge

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@frontend/src/__tests__/recommendations-permissions.test.ts`:
- Around line 340-351: Strengthen the readonly DOM assertions in
frontend/src/__tests__/recommendations-permissions.test.ts at lines 340-351 by
asserting the first header cell and first summary-row cell are checkbox-col
elements, while preserving the existing count and chevron checks. At lines
520-524, assert each child row’s first cell is td.checkbox-col and has empty
text content; no other sites require changes.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 736b3ed9-69bd-4003-b8ba-b766b552a4f9

📥 Commits

Reviewing files that changed from the base of the PR and between bef2d0e and e43b989.

📒 Files selected for processing (2)

• frontend/src/__tests__/recommendations-permissions.test.ts
• frontend/src/recommendations.ts

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