Refactor and update Soundscape Analysis documentation structure

[MitchellAcoustics]

This pull request significantly improves the documentation for Soundscapy, making it more accessible to new users and clarifying key concepts, usage patterns, and module structure. The changes include a new conceptual overview, reorganization of introductory material, enhanced installation instructions, and updates to tutorials and examples for clarity and accuracy.

Major documentation improvements:

Conceptual and Getting Started Content:

• Added a new background.md file that introduces soundscape analysis concepts, the ISO 12913 circumplex model, and the rationale for distributional analysis, providing essential context for new users.
• Updated index.md to clarify what Soundscapy does, highlight its main capabilities, and provide a more user-friendly installation guide, including clearer instructions for optional dependencies and where to begin.
• Improved the "Contributing" and "License" sections in index.md for better clarity and navigation.

Reference and Tutorials:

• Enhanced the API reference in reference/index.md to use a table format, summarizing each public module, its purpose, and its requirements.
• Improved the tutorials index (tutorials/index.md) by adding a "Where to start" section and linking to the new conceptual overview, making it easier for users to find relevant guides.

Examples and Usage Corrections:

• Updated example notebooks to correct API usage (e.g., using the correct submodules for mean_responses, ssm_metrics, and likert_data_quality), clarify the purpose of the SATP module, and improve code clarity and dataset paths. [1] [2] [3] [4] [5] [6] [7] [8]

Other Documentation Updates:

• Cleaned up the news page by removing outdated release notes, focusing on recent and relevant changes.

These changes collectively make the documentation more welcoming and actionable for both new and experienced users, while ensuring accuracy and consistency across guides and examples.

[Copilot]

Pull request overview

This PR reorganizes and expands Soundscapy’s documentation to improve onboarding and clarify module responsibilities, while also updating several example notebooks and a small deprecation note in the SATP CircE API docs.

Changes:

• Adds a new conceptual overview page (“About Soundscape Analysis”) and updates navigation/index pages for a clearer “where to start” flow.
• Updates tutorial/example notebooks to correct API usage and align dataset paths around a bundled demo Excel file.
• Tweaks Pixi test task commands and refreshes some docstring deprecation messaging.

Reviewed changes

Copilot reviewed 14 out of 18 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
zensical.toml	Reworks site nav structure (new conceptual page; renamed/reshuffled tutorials; plotting nav cleanup).
src/soundscapy/satp/circe.py	Updates deprecation notice formatting in from_bfgs() docstring.
pixi.toml	Adjusts pytest invocation/flags handling for test tasks.
examples/QuickStart.ipynb	Fixes narrative text to reference ISOPlot and minor output formatting.
examples/IoA_Soundscape_Assessment_Tutorial_v2.ipynb	Removes Colab/install noise and standardizes demo data path usage.
examples/HowToAnalyseAndRepresentSoundscapes.ipynb	Updates/normalizes some rendered outputs and cell formatting.
examples/data/DemoData.xlsx	Adds a bundled demo dataset used by multiple tutorials.
examples/6_Soundscape_Assessment_Tutorial.ipynb	Standardizes demo data path and replaces placeholder plotting calls with real examples.
examples/5_Working_with_Soundscape_Databases.ipynb	Updates database/SATP-related examples and corrects survey API usage in later sections.
docs/tutorials/index.md	Adds “Where to start” table and refreshes tutorial descriptions/links.
docs/reference/index.md	Converts API reference index to a table summary of modules.
docs/news.md	Removes outdated plotting-module news entry.
docs/index.md	Rewrites homepage to clarify capabilities, installs, and entry points.
docs/CHANGELOG.md	Adds an “Unreleased” section summarizing the docs overhaul and related changes.
docs/background.md	Adds new conceptual overview of soundscape analysis and ISO circumplex coordinates.

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