…es (#14688)

* feat: avatar s3 feature for discussions app

* feat(cli): generate per-table stacks for multiple DDB tables

Previously, all DynamoDB tables were placed in a single shared storage
stack, causing conflicts when multiple tables existed. Each DDB table
now gets its own nested stack via backend.createStack('storage<name>'),
matching the Gen1 nested stack naming convention.

Also fixes resolveOutputs() crash when a Gen2 storage stack has no
Outputs section (happens when no cross-stack references exist for a
table).

Closes #14608, #14597

* fix(discussions): replace hand-crafted snapshots with real infrastructure data

Recapture discussions app snapshots from live deployments:
- Gen1: amplify-discussionsblade-blade-4edfd (activity + bookmarks tables)
- Gen2: amplify-d1skq8aomhb772-e2etest-branch (per-table stacks)

Pre-generate inputs use real amplify-pull data for bookmarks resource.
Pre-refactor templates fetched from deployed CloudFormation stacks.
Post-generate and post-refactor regenerated by test framework.

Also adds bookmarks to migration-config.json and fixes snapshot.ts
to use TemplateStage: Original for unprocessed templates.

* docs(discussions): add bookmarks table setup instructions to README

* fix(discussions): sanitize Amplify App ID in Gen2 snapshot files

Replace raw app ID d1skq8aomhb772 with sanitized name 'discussions'
in all snapshot file contents and filenames.

* docs(discussions): add S3 avatars bucket to migration config

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* test(discussions): update snapshots with S3 avatars + bookmarks DDB

Re-deployed discussions app with 3 storage types (activity DDB,
bookmarks DDB, avatars S3) and captured fresh snapshots for all 4
stages. Per-table stacks refactor verified working for both DDB tables.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(cli): disambiguate S3 nested stack from DDB per-table stacks

The S3 forward/rollback refactorers used findNestedStack with a bare
'storage' prefix, which matched DDB per-table stacks (e.g.
'storageactivity') before the S3 stack ('storage0EC3F24A'). Fixed by
using 'storage' + resourceName for Gen1 lookup and a new
findS3NestedStack method that distinguishes the CDK-hashed S3 stack
from lowercase-prefixed DDB stacks for Gen2 lookup.

Also refreshes discussions snapshots from a clean main/gen2-main deploy.

* fix(cli): address PR review comments for per-table stacks

- Replace fragile char-based findS3NestedStack with template-based S3
  detection (fetch template, check for AWS::S3::Bucket resource)
- Export findS3NestedStack from storage-forward.ts, import in rollback
- Remove dead STORAGE_RESOURCE_TYPES export
- Remove storage:S3 from validateSingleResourcePerStack (only one
  defineStorage() possible)
- Make scopeVarName required (no default) in DynamoDBRenderer
- Set Outputs default empty object in cfn-output-resolver, use
  templateOutputs consistently
- Add comments for optional Outputs in cfn-template.ts and resolver

* fix(cli): restore storage:S3 case in validateSingleResourcePerStack

Keep S3 validation as a defensive spot check even though the collision
can't happen in practice (JSON key uniqueness prevents same-name
resources within a category).

* feat(cli): add S3 avatars and bookmarks DDB tests to discussions test script

Extends the discussions gen1 test script to cover all stateful resources
that get refactored during migration: S3 avatars bucket (upload/getUrl/remove)
and bookmarks DynamoDB table (put/get/delete via AWS SDK). Verified with
full forward→rollback→forward round-trip on live app.

* refactor(cli): clean up bookmarks test - shared DDB client, config-based table lookup

Remove ListTablesCommand discovery in favor of reading table name from
amplifyconfiguration.json. Share a single DynamoDBDocumentClient across
all bookmark test functions instead of creating one per call.

* chore(cli): remove dev-only .gitignore from amplify-cli package

Remove .gitignore that ignored local dev helper scripts
(add-bookmarks.ts, deploy-gen1.ts) that no longer exist.

* fix(cli): add typescript devDep to fix typecheck for bundler moduleResolution

backend-only and discussions were missing typescript as a
devDependency, causing npx tsc to fall back to the root
tsc v4.9.5 which doesn't support moduleResolution:"bundler".
Also restores monorepo metadata in discussions snapshot
package.json files.

* fix: use README-specified emailVerificationMessage in discussions snapshots

Replace "Your verification code is {####}" with "Here is your verification code
{####}" to match the discussions README instructions, preventing drift when
snapshots are regenerated.

* fix: replace remaining old verification message in discussions snapshots

* fix: align gen2 branch verification messages with README

* fix: revert SMS verification messages to original values

Only email verification fields should use the README-specified message.
SMS fields should retain their original values.

* fix: remove trailing newlines from parameters files

* fix: remove unnecessary typescript devDependency from migration apps

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>