ci(dependabot): surface major npm updates as one grouped weekly PR (#11307)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - Dependabot keeps the npm dependency tree and the GitHub Actions
workflows current with weekly update PRs
> - The npm config ignores every major version bump with a wildcard
`ignore` rule, and no other process reports pending majors
> - Major-version debt grows silently, and ignore rules also suppress
Dependabot security updates when the fix ships only in a newer major
> - Individual major PRs are not a good replacement: the board decided
in #7560 to keep the PR list mergeable, and a flood of breaking bumps
works against that
> - This pull request removes the blanket ignore and groups all pending
majors into one weekly PR, while minors and patches keep one PR per bump
> - The benefit is a standing, visible signal of pending major updates,
at a cost of at most one extra PR per week

## Linked Issues or Issue Description

**What existing behavior does this improve?**

The Dependabot npm update flow configured in `.github/dependabot.yml`.

**Current behavior**

Dependabot opens weekly PRs for minor and patch npm updates. A wildcard
`ignore` rule suppresses every major version update. No report or
reminder replaces the suppressed PRs — the comment says "review those
manually", but nothing triggers that review. Ignore rules also apply to
Dependabot security updates, so a security fix that ships only in a
newer major is suppressed as well.

**Proposed behavior**

Dependabot opens one grouped weekly PR that contains every pending major
npm update. Minor and patch updates keep their current one-PR-per-bump
flow. A deliberate hold on a specific major can use a targeted
per-dependency `ignore` entry instead of the wildcard.

**Reason and benefit**

Silent major-version drift compounds: each skipped major makes the
eventual upgrade jump larger and riskier, especially across
peer-dependency families. A single grouped PR makes the backlog visible
in the PR list without flooding it. When the grouped PR is green, it
merges cheaply. When it is red, it is a visible standing task instead of
invisible debt.

**Breaking changes**

None. This changes repository automation only. Runtime behavior,
response shapes, and outputs are unchanged.

**Additional context**

Related history: #7483 grouped patch/minor updates by dependency type,
and #7560 reverted that grouping because the resulting 26-package PR was
hard to merge. This PR does not touch the patch/minor flow. It only
groups majors, which currently produce no PRs at all — it adds a signal
that does not exist today rather than replacing individually mergeable
PRs.

## What Changed

- Removed the wildcard `ignore` rule for `version-update:semver-major`
from the npm ecosystem in `.github/dependabot.yml`.
- Added a `major-updates` group (`applies-to: version-updates`,
`update-types: ["major"]`, `patterns: ["*"]`) so all pending majors land
in one weekly grouped PR.
- Left the schedule, labels, PR limits, and the github-actions ecosystem
unchanged.

## Verification

- `npx js-yaml .github/dependabot.yml` parses cleanly and the `groups`
stanza follows the Dependabot v2 schema (`applies-to`, `update-types`,
`patterns`).
- After merge: check Insights → Dependency graph → Dependabot for config
errors. The next weekly run (Monday 06:00) opens a single
`major-updates` grouped PR that lists the pending majors.
- No code changed, so the test suite is unaffected.

## Risks

- Low risk. This is CI/automation configuration only.
- The first grouped PR may be large, and red if several majors break the
build. That is the intended visibility mechanism, and it does not block
other work. A noisy or deliberately held-back dependency can be excluded
from the group with `exclude-patterns` or a targeted per-dependency
`ignore` entry.
- This does not regroup minors or patches, so it does not reintroduce
what #7560 reverted.

## Model Used

- Claude Fable 5 (Anthropic), model ID `claude-fable-5`, via Claude Code
CLI, extended thinking and tool use enabled.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [ ] I have run tests locally and they pass — N/A, YAML-only CI config
change; validated with `js-yaml`
- [ ] I have added or updated tests where applicable — N/A, no code
changed
- [x] I have updated relevant documentation to reflect my changes — none
reference the Dependabot config
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green — one e2e shard flaked on an
unrelated MCP UI spec and passed on re-run with identical code
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

.github/dependabot.yml

@@ -9,10 +9,16 @@ updates:
     open-pull-requests-limit: 10
     labels:
       - "dependencies"
-    ignore:
-      # Ignore major version bumps — review those manually
-      - dependency-name: "*"
-        update-types: ["version-update:semver-major"]
+    groups:
+      # Bundle all major version bumps into a single weekly PR so they
+      # stay visible without flooding the PR list. Minor/patch updates
+      # still get individual PRs.
+      major-updates:
+        applies-to: version-updates
+        update-types:
+          - "major"
+        patterns:
+          - "*"
 
   - package-ecosystem: github-actions
     directory: "/"