fix(infra): distinct Aurora construct ID; group + unpause Dependabot (#129)

* fix(infra): give the Aurora cluster a distinct construct ID

The RDS->Aurora swap (PR3 #125) kept construct ID 'Database', so CloudFormation
saw the same logical ID change from AWS::RDS::DBInstance to AWS::RDS::DBCluster and
rejected the changeset ('Update of resource type is not permitted'). Renaming the
construct to 'AuroraCluster' gives the cluster a new logical ID, so CFN does a clean
replace (remove old DBInstance, add new DBCluster) instead of an in-place type change.

* chore(deps): group Dependabot minor/patch updates per ecosystem

Add a group to each update entry so weekly minor/patch bumps land as a
single PR per ecosystem/directory instead of one PR per package. Major
bumps remain individual PRs so breaking changes get isolated review.

Grouping takes effect when open-pull-requests-limit is raised above 0
(version updates are still paused during development, #109).

* chore(deps): unpause Dependabot version updates

Raise open-pull-requests-limit from 0 to 10 across all ecosystems,
re-enabling weekly version updates (paused during development, #109).
With grouping now in place, minor/patch bumps land as one grouped PR
per ecosystem; the limit caps outstanding major-bump PRs.

.github/dependabot.yml

@@ -4,74 +4,141 @@ updates:
     directory: /infra
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      infra:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: npm
     directory: /web
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      web:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: npm
     directory: /mobile
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      mobile-npm:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: bundler
     directory: /mobile
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      mobile-bundler:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: nuget
     directory: /api
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      api:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: pip
     directory: /lambdas/pdf-extract
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      pdf-extract:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: pip
     directory: /lambdas/pdf-generate
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      pdf-generate:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: pip
     directory: /lambdas/library-ingest
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      library-ingest:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: pip
     directory: /lambdas/suggestions
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      suggestions:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: pip
     directory: /lambdas/oss-index-creator
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
-
+    groups:
+      oss-index-creator:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: github-actions
     directory: /
     schedule:
       interval: weekly
-    open-pull-requests-limit: 0
+    open-pull-requests-limit: 10
+    groups:
+      github-actions:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"

infra/lib/foundation-stack.ts

@@ -88,7 +88,11 @@ export class FoundationStack extends cdk.Stack {
     // PR3: replaced the RDS instance + OpenSearch Serverless with Aurora + pgvector
     // (kills the AOSS OCU floor; scales toward 0 ACU when idle). Data API is required
     // by Bedrock Knowledge Bases to query the vector table.
-    const dbCluster = new rds.DatabaseCluster(this, 'Database', {
+    // Construct ID is 'AuroraCluster' (not 'Database') so CloudFormation gets a NEW
+    // logical ID for the cluster — the old RDS DBInstance shared logical ID 'Database*'
+    // and CFN forbids changing a resource's type in place ("Update of resource type is
+    // not permitted"). A distinct ID makes it a clean replace instead.
+    const dbCluster = new rds.DatabaseCluster(this, 'AuroraCluster', {
       clusterIdentifier: `proposal-system-db${config.stackSuffix}`,
       engine: rds.DatabaseClusterEngine.auroraPostgres({
         version: rds.AuroraPostgresEngineVersion.VER_15_4,