docs: restructure README (970→159 lines) with docs/ folder

Extract advanced content to 7 focused docs/ files. Zero content removed.

README: Quick Start → Installation → Configuration → Troubleshooting
(moved from line 902 to 98) → Standalone API → Advanced Topics links.

docs/:
- configuration.md — all 17 config options
- organization.md — groups, sections, cropping, multi-env
- drivers.md — VIPS, ChunkyPNG, perceptual threshold
- framework-setup.md — Minitest, RSpec, Cucumber
- ci-integration.md — manual setup, reusable action, baseline updates
- reporters.md — HTML report, custom reporters
- docker-testing.md — bin/dtest, recording baselines

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pftg

.github/actions/upload-screenshots/action.yml

@@ -20,18 +20,25 @@ runs:
         name: ${{ inputs.name }}-diffs
         retention-days: ${{ inputs.retention-days }}
         path: test/fixtures/app/doc/screenshots/
+        if-no-files-found: ignore
 
     - name: Upload Capybara failure screenshots
       uses: actions/upload-artifact@v7
       with:
         name: ${{ inputs.name }}-capybara-fails
         retention-days: ${{ inputs.retention-days }}
         path: tmp/capybara/screenshots-diffs/
+        if-no-files-found: ignore
 
     - name: Check for HTML report
       id: check-report
       shell: bash
-      run: test -f "${{ inputs.report-path }}/index.html" && echo "exists=true" >> "$GITHUB_OUTPUT" || echo "exists=false" >> "$GITHUB_OUTPUT"
+      run: |
+        if [ -f "${{ inputs.report-path }}/index.html" ]; then
+          echo "exists=true" >> "$GITHUB_OUTPUT"
+        else
+          echo "exists=false" >> "$GITHUB_OUTPUT"
+        fi
 
     - name: Upload HTML report (inline preview)
       if: steps.check-report.outputs.exists == 'true'

.github/workflows/test.yml

@@ -86,13 +86,13 @@ jobs:
           name: base-screenshots
 
       - name: Find existing report comment
-        if: failure() && github.event_name == 'pull_request'
+        if: always() && github.event_name == 'pull_request'
         uses: peter-evans/find-comment@v3
         id: find-comment
         with:
           issue-number: ${{ github.event.pull_request.number }}
           comment-author: 'github-actions[bot]'
-          body-includes: 'Screenshot diffs detected'
+          body-includes: 'Screenshot diffs'
 
       - name: Comment PR with report link
         if: failure() && github.event_name == 'pull_request'
@@ -104,9 +104,22 @@ jobs:
           body: |
             ### Screenshot diffs detected
 
-            [View HTML report](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}#artifacts) in Actions artifacts.
+            | Artifact | Description |
+            |----------|-------------|
+            | [`base-screenshots-report`](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}#artifacts) | Inline HTML report (click to view in browser) |
+            | [`base-screenshots-report-full`](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}#artifacts) | Full report with images (download for offline review) |
+            | [`base-screenshots-diffs`](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}#artifacts) | Raw screenshot diff files |
+
+      - name: Update comment on success
+        if: success() && github.event_name == 'pull_request' && steps.find-comment.outputs.comment-id != ''
+        uses: peter-evans/create-or-update-comment@v5
+        with:
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          edit-mode: replace
+          body: |
+            ### Screenshot diffs resolved
 
-            Click `base-screenshots-report` for inline preview, or download `base-screenshots-report-full` for images.
+            All screenshots match their baselines. Previous diffs have been fixed.
 
       - name: Uploading Coverage Report
         uses: actions/upload-artifact@v7