Python Documentation: Follow-up improvements from PR #403

## Overview

This issue tracks follow-up improvements for the Python documentation section that were identified during the review of PR #403.

**Related PR:** #403
**Requested by:** @amotl

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## Backlog Items

### 1. Add Runnable Examples to Python Clients

**Context:** [PR #403 comment](https://github.com/crate/cratedb-guide/pull/403#discussion_r1813234567)

Provide runnable examples for each Python client by either:
- Adding inline dependencies using PEP 723 (implemented by `uv`)
- Adding simple `pip install ...` incantations to the docs, followed by invocation instructions

This approach has been conducted for other clients, so the Python area should not be left behind.

**Affected files:**
- `docs/connect/python/crate-python.md` and similar client documentation pages

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### 2. Expand DataFrame Libraries Documentation

**Context:** [PR #403 comment](https://github.com/crate/cratedb-guide/pull/403#discussion_r1813235890)

**Tasks:**
- Expand DataFrame libraries (Dask, pandas, Polars) into individual dedicated pages
- Absorb content from the "integrations" section
- Absorb content from SQLAlchemy dialect's DataFrame operations documentation:
- https://cratedb.com/docs/sqlalchemy-cratedb/dataframe.html

**Affected files:**
- `docs/connect/python/index.md`
- Create new pages for each DataFrame library

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### 3. Review and Incorporate Content from GH-138

**Context:** [PR #403 comment](https://github.com/crate/cratedb-guide/pull/403#discussion_r1821567432)

Review content from the patch in issue #138 before finalizing the Python documentation section.

**Reference:** #138

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### 4. Improve Python Presentation Inspired by DuckDB

**Context:** [PR #403 comment](https://github.com/crate/cratedb-guide/pull/403#discussion_r1831245789)

DuckDB provides an excellent example of how to organize driver documentation across different domains and connectivity options:
- https://duckdb.org/docs/stable/clients/python/overview

Consider improving our Python presentation using similar organizational patterns.

**Affected files:**
- `docs/connect/python/index.md` and related structure

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## Notes

These items were deferred from PR #403 to keep the initial refactoring focused. They represent enhancements and additional content that will further improve the Python documentation section.