build: fixup 2.102.0 release prep (asserts + missed changesets)

[dannimad]

Description

Two follow-ups after #27399, #27400, #27401 merged:

1. Six new untagged asserts in @fluidframework/tree

Landed via #27200 (field batch format work):

• packages/dds/tree/src/feature-libraries/chunked-forest/codec/chunkDecoding.ts (5)
• packages/dds/tree/src/simple-tree/core/treeNodeKernel.ts (1)

Tagged with codes 0xcfb–0xd00 via pnpm run policy-check:asserts.

2. Two changesets missed by #27401's release-notes generation

.changeset/soft-beds-beam.md and .changeset/zesty-otters-collab.md from
#27212 landed after I ran the release-notes generation locally but before
#27401 merged, so they were not picked up by the 2.102.0 release notes or
changelogs.

Followed the documented revert-and-regenerate flow from
.claude/skills/fluid-release/references/minor-release-prep.md:

1. Reverted build: add release notes and changelogs for 2.102.0 #27401 (squash commit cf7e1891a4) to restore the two original
   changesets.
2. Ran pnpm flub generate releaseNotes -g client -t minor (now sees all 4).
3. Ran pnpm flub generate changelog -g client (consumes all 4 changesets).
4. Manually fixed PR/commit refs for the two restored changesets — flub had
   pointed them at the revert commit (5b7ce7075f / #27401) instead of their
   original PRs. Corrected in:
   • packages/framework/fluid-framework/CHANGELOG.md → Promote onAssertionFailure to beta #27282 / 4191b82e41
   • packages/common/core-utils/CHANGELOG.md → Promote onAssertionFailure to beta #27282 / 4191b82e41
   • packages/common/container-definitions/CHANGELOG.md → feat: add optional getPendingLocalState to IContainer #27269 / 1f12b8e36e

The two new changesets (soft-beds-beam, zesty-otters-collab) keep correct
refs from their original PR #27212.

Merge order

This PR must merge before #27402 (the 2.103.0 version bump).
After this merges, #27402 will need a rebase onto updated main (new
packageVersion.ts files added by #27200 also need to bump to 2.103.0).

Reviewer Guidance

The review process is outlined on this wiki page.

Please skim RELEASE_NOTES/2.102.0.md — it should now have 4 entries across
✨ Features (1), Legacy API Changes (1), Deprecations (1), and Legacy (1).

[github-actions]

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Based on the diff (126 lines, 11 files), I've queued these reviewers:

• Correctness — logic errors, race conditions, lifecycle issues
• Security — vulnerabilities, secret exposure, injection
• API Compatibility — breaking changes, release tags, type design
• Performance — algorithmic regressions, memory leaks
• Testing — coverage gaps, hollow tests

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[github-actions]

🔗 No broken links found! ✅

Your attention to detail is admirable.

linkcheck output

> fluid-framework-docs-site@0.0.0 ci:check-links /home/runner/work/FluidFramework/FluidFramework/docs
> start-server-and-test "npm run serve -- --no-open" 3000 check-links

1: starting server using command "npm run serve -- --no-open"
and when url "[ 'http://127.0.0.1:3000' ]" is responding with HTTP status code 200
running tests using command "npm run check-links"


> fluid-framework-docs-site@0.0.0 serve
> docusaurus serve --no-open

[SUCCESS] Serving "build" directory at: http://localhost:3000/

> fluid-framework-docs-site@0.0.0 check-links
> linkcheck http://localhost:3000 --skip-file skipped-urls.txt

Crawling...

Stats:
  288859 links
    1925 destination URLs
    2175 URLs ignored
       0 warnings
       0 errors