Add Monzo spent today sensor

[JakeMartin-ICL]

Proposed change

Add an account-level Spent today monetary sensor to the Monzo integration. The Monzo API reports spending as a negative minor-unit value, so the sensor exposes its magnitude as a positive currency value to make its meaning clear to users.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Document Monzo spent today sensor home-assistant.io#47385
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running: python3 -m script.gen_requirements_all.
• For the updated dependencies a diff between library versions and ideally a link to the changelog/release notes is added to the PR description.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[Copilot]

Pull request overview

Adds account-level “Spent today” monetary sensors to the Monzo integration.

Changes:

• Converts negative minor-unit spending into positive currency values.
• Adds localized entity naming and test fixtures.
• Extends entity snapshots for current and Flex accounts.

Reviewed changes

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

Show a summary per file

File	Description
homeassistant/components/monzo/sensor.py	Defines the new sensor.
homeassistant/components/monzo/strings.json	Adds its translated name.
tests/components/monzo/conftest.py	Adds spending fixture data.
tests/components/monzo/test_sensor.py	Verifies value conversion.
tests/components/monzo/snapshots/test_sensor.ambr	Captures new entities and states.

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