fix typos, update docs

[anna-follestad-4ss]

What changed

Fix typos and update docs that I had forgotten to do.

Why

There were inconsistencies and typos in the docs.

Definition of done

CI covers the first two. The rest are yours — tick them because you did them,
not because they were already ticked. See CONTRIBUTING.md for why each is here.

• pytest passes
• black is clean
• Every threshold, unit and label comes from a named constant, not a literal
• Anything machine-specific is in .env.example, not hardcoded (unless it's
  a documented, deliberate simplification - see README)
• Every page opened and looked at after the change
• At least one displayed number spot-checked against the source
• CLAUDE.md updated if this establishes a new convention, README.md if it
  changes how to run, refresh or deploy anything

Anything the reviewer should look at closely

Make sure contributing and readme match the current version of the app

[Copilot]

Pull request overview

This PR updates repository documentation to reflect the current runtime defaults and configuration surface of the Dash app (notably the default port and environment variables), and refreshes a few repo-reference docs/templates accordingly.

Changes:

• Update local run instructions to use port 5050 (matching src/app.py’s default PORT).
• Refresh configuration docs to list the current .env variables (DASH_DEBUG, PORT, MOCK_PLATFORM_HEADER, MOCK_PLATFORM_SPACER, LOG_MEMORY).
• Add memory_log.py to the documented repository file structure and simplify the PR template’s “definition of done” preamble.

Reviewed changes

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

File	Description
README.md	Updates run URL/port and documents the full .env configuration set; adds memory_log.py to the repo layout section.
CONTRIBUTING.md	Updates the “run the app” note to reflect :5050.
CLAUDE.md	Updates the documented file structure to include memory_log.py.
.github/pull_request_template.md	Simplifies the “Definition of done” preamble while keeping the checklist intact.

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