feat: switch to simpler version stamp method

[GordonSmith]

Checklist:

• The commit message is properly formatted and free of typos.
  • The commit message title makes sense in a changelog, by itself.
  • The commit message includes a "fixes" reference if appropriate.
  • The commit is signed.
• The change has been fully tested:
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• There are no similar instances of the same problem that should be addressed
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Testing:

[Copilot]

Pull Request Overview

This PR replaces the pre-build version stamping system with a Rollup plugin-based approach that injects version information during the build process. Instead of generating __package__.ts files with hardcoded version strings before building, the new system uses placeholder strings that are replaced by a Rollup plugin at build time.

Key changes:

• Introduced a new packageVersionPlugin Rollup plugin that replaces version placeholders during the build
• Replaced hardcoded version strings with placeholder constants in all __package__.ts files
• Removed the separate "stamp" build step from all package.json scripts and CI workflows

Reviewed Changes

Copilot reviewed 100 out of 101 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
utils/bundle/src/rollup-plugin-version.ts	New Rollup plugin that reads package.json and replaces version placeholders during build
utils/bundle/src/stamp.js	Removed pre-build stamping script
utils/bundle/src/stamp-main.js	Removed pre-build stamping script for root package
utils/bundle/src/index.ts	Exports the new packageVersionPlugin
utils/bundle/package.json	Added rollup as a devDependency
packages/*/src/__package__.ts	Changed hardcoded version strings to placeholders
packages/*/rollup.config.mjs	Added packageVersionPlugin to build pipeline
packages/*/package.json	Removed "stamp" scripts
packages/dgrid-shim/webpack.config.js	Added string-replace-loader to handle version placeholders in Webpack build
packages/dgrid-shim/package.json	Added string-replace-loader dependency
package.json	Removed stamp-related scripts and bumped version
.github/workflows/release-please.yml	Removed stamp-related build steps

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