fix(ci): workflow reliability and architecture improvements

- Reconstruct e2e-tests-split.yml to match spec (15 jobs, security isolation)
- Update docker-build.yml to authenticate Docker Hub for PRs (fixes 401)
- Refactor propagate-changes.yml to enforce strict hierarchy (Pittsburgh model)
- Implement API-based loop prevention to stop rebase loops

Ref: #660

.github/workflows/propagate-changes.yml

@@ -5,6 +5,7 @@ on:
     branches:
       - main
       - development
+      - 'feature/**'
       - 'hotfix/**'
 
 concurrency:
@@ -35,6 +36,25 @@ jobs:
         with:
           script: |
             const currentBranch = context.ref.replace('refs/heads/', '');
+            let excludedBranch = null;
+
+            // Loop Prevention: Identify if this commit is from a merged PR
+            try {
+              const associatedPRs = await github.rest.repos.listPullRequestsAssociatedWithCommit({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                commit_sha: context.sha,
+              });
+
+              // If the commit comes from a PR, we identify the source branch
+              // so we don't try to merge changes back into it immediately.
+              if (associatedPRs.data.length > 0) {
+                excludedBranch = associatedPRs.data[0].head.ref;
+                core.info(`Commit ${context.sha} is associated with PR #${associatedPRs.data[0].number} coming from '${excludedBranch}'. This branch will be excluded from propagation to prevent loops.`);
+              }
+            } catch (err) {
+              core.warning(`Failed to check associated PRs: ${err.message}`);
+            }
 
             async function createPR(src, base) {
               if (src === base) return;
@@ -148,22 +168,35 @@ jobs:
 
             if (currentBranch === 'main') {
               // Main -> Development
-              await createPR('main', 'development');
+              // Only propagate if development is not the source (loop prevention)
+              if (excludedBranch !== 'development') {
+                await createPR('main', 'development');
+              } else {
+                core.info('Push originated from development (excluded). Skipping propagation back to development.');
+              }
             } else if (currentBranch === 'development') {
-              // Development -> Feature branches (direct, no nightly intermediary)
+              // Development -> Feature/Hotfix branches (The Pittsburgh Model)
+              // We propagate changes from dev DOWN to features/hotfixes so they stay up to date.
+
               const branches = await github.paginate(github.rest.repos.listBranches, {
                 owner: context.repo.owner,
                 repo: context.repo.repo,
               });
 
-              const featureBranches = branches
+              // Filter for feature/* and hotfix/* branches using regex
+              // AND exclude the branch that just got merged in (if any)
+              const targetBranches = branches
                 .map(b => b.name)
-                .filter(name => name.startsWith('feature/'));
+                .filter(name => {
+                  const isTargetType = /^feature\/|^hotfix\//.test(name);
+                  const isExcluded = (name === excludedBranch);
+                  return isTargetType && !isExcluded;
+                });
 
-              core.info(`Found ${featureBranches.length} feature branches: ${featureBranches.join(', ')}`);
+              core.info(`Found ${targetBranches.length} target branches (excluding '${excludedBranch || 'none'}'): ${targetBranches.join(', ')}`);
 
-              for (const featureBranch of featureBranches) {
-                await createPR('development', featureBranch);
+              for (const targetBranch of targetBranches) {
+                await createPR('development', targetBranch);
               }
             }
         env: