Chore: immutable yarn install

[katspaugh]

• Add --immutable to all install commands
• Explicitly install typedoc as a dev dependency instead of an ad-hoc install during the build

[Copilot]

Pull Request Overview

This PR standardizes the project's dependency installation process by adding the --immutable flag to all yarn install commands and explicitly declaring typedoc as a dev dependency instead of installing it ad-hoc during builds.

• Adds --immutable flag to all yarn install commands in CI workflows
• Moves typedoc from ad-hoc installation to explicit dev dependency in package.json
• Standardizes package manager usage from mixed npm/yarn to consistent yarn usage

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
package.json	Adds typedoc as explicit dev dependency
.github/workflows/typedoc.yml	Replaces npm commands with yarn install --immutable and removes ad-hoc typedoc install
.github/workflows/test.yml	Updates npm install to yarn install --immutable
.github/workflows/lint.yml	Adds --immutable flag to existing yarn install command

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