build(deps): switch to caret version pinning for npm dependencies

Change package.json to use caret (^) pinning for flexible version
resolution. Packages >=1.0.0 pin to major version, packages <1.0.0
pin to minor version.

The following packages remain exact-pinned due to compatibility issues:

- redux (3.7.2) and redux-thunk (2.2.0): Newer versions of redux-thunk
  (2.3+) require redux@^4 as a peer dependency. Since the codebase uses
  redux 3.x, allowing redux-thunk to upgrade would cause peer dependency
  conflicts and potential runtime issues.

- @edx/frontend-component-cookie-policy-banner (2.2.0): Newer versions
  (2.6.0+) depend on @openedx/[email protected] which requires PNG file loaders
  and uses SCSS files incompatible with the current webpack/sass-loader
  configuration.

- bootstrap (4.0.0): Newer versions (4.6.x) use a `deprecate` mixin in
  their SCSS that the current sass compilation setup doesn't support.

- [email protected]: Newer 2.x versions (2.99+) enforce stricter
  afterEach placement rules that break edx-ui-toolkit's ajax-helpers.js

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: feanil