ENH: Add native Meteomatics API support to the Environment class

[Gui-FernandesBR]

Pull request type

• Code changes (feature, bug fix, etc.)

Checklist

• Tests have been added (fully mocked — no real API calls, no charges)
• Docs have been added / updated
• CHANGELOG.md has been updated

Description

Closes #545.

Brings native Meteomatics weather-API support into the Environment class,
porting and generalizing the implementation that already lived in the
EuRoC-Dev repository. The API model mirrors the existing Windy integration
(a fetcher + a process_*_atmosphere method).

Usage:

env.set_atmospheric_model(
    type="Meteomatics",
    file="mix",              # Meteomatics weather model
    username="your_username",
    password="your_password",
)

Credentials fall back to the METEOMATICS_USERNAME / METEOMATICS_PASSWORD
environment variables when the kwargs are omitted.

What was added

• rocketpy/environment/fetchers.py
  • fetch_meteomatics_token — authenticates with username/password and
    obtains a short-lived access token.
  • fetch_atmospheric_data_from_meteomatics — queries temperature, pressure
    and both wind components at several heights above ground level, grouping
    parameters to respect the account's per-request limit.
• rocketpy/environment/environment.py
  • process_meteomatics_atmosphere — converts the height-AGL data to
    above-sea-level profiles using the Environment elevation and sets the
    pressure/temperature/wind functions.
  • set_atmospheric_model gains username / password kwargs and a
    "meteomatics" case; to_dict / from_dict round-trips the new type.

Notes on the two points raised in the issue

1. Allow users to use the Meteomatics API when creating Environment objects —
   done via type="Meteomatics".
2. Test the feature without being charged — every test fully mocks the HTTP
   layer (the requests.get call in the fetcher tests, and the fetcher itself
   in the Environment tests), so no real requests are made.

Robustness

• Network requests use timeouts.
• Deterministic client errors (4xx) are not retried and surface actionable
  RuntimeError messages (invalid model, out-of-range altitude, bad
  credentials, malformed response); transient/5xx errors are retried with
  backoff.

Authentication note

Meteomatics does not use a static API token: you authenticate with a personal
username + password and a short-lived bearer token is generated automatically.
That is what the username / password arguments carry.

[Copilot]

Pull request overview

Adds first-class Meteomatics Weather API support to RocketPy’s Environment, following the existing “fetcher + process_*_atmosphere” integration style and enabling fully mocked tests/docs for the new workflow.

Changes:

• Implement Meteomatics authentication + grouped profile fetching in rocketpy/environment/fetchers.py.
• Add Environment.process_meteomatics_atmosphere() and wire "meteomatics" into set_atmospheric_model() and (de)serialization metadata handling.
• Add unit tests (fully mocked), user docs, and a changelog entry for the new API support.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
rocketpy/environment/fetchers.py	Adds Meteomatics token and atmospheric-profile fetching logic with retries/timeouts and parameter grouping.
rocketpy/environment/environment.py	Adds Meteomatics atmospheric model processing and integrates it into the Environment model selection and restore path.
tests/unit/environment/test_fetchers.py	Adds mocked unit tests covering Meteomatics token retrieval, grouping/parsing, and error handling.
tests/unit/environment/test_environment.py	Adds unit tests validating Meteomatics integration behavior in Environment (profiles, env-var credentials, edge cases).
docs/user/environment/3-further/other_apis.rst	Documents Meteomatics usage and configuration options for users.
CHANGELOG.md	Records the feature addition in the changelog.