docs(python): embedded bindings page and quickstart connection options - #503

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The red "Validate Documentation" check is the same as on main (the last two Documentation Validation runs on main, 64ee576 and b9addec, fail too): 2 anchor names in reference/sql/sql-functions.adoc (cchShortestPath, duanSSSP) and 3 broken cross-references in how-to/connectivity/postgres.adoc:186, reference/settings.adoc:553 and reference/sql/chapter.adoc:66. This PR adds no error; the only change in the output is one more "potentially orphaned" warning, because the validator counts <<>> references and the new page is linked with xref:, like the other driver pages. The site build passes and shows the new page.

Heads-up on the package names. This page says arcadedb-embedded (import name arcadedb_embedded) and points to the arcadedb-embedded-native preview. With the 26.11.1 release the bindings (ArcadeData/arcadedb-python) ship as arcadedb (native build, the default) and arcadedb-jvm (JVM build). Both import as arcadedb. The old name arcadedb-embedded gets a deprecation shim that points to the new packages.

What changes on the page: the install lines, the import line in the two samples, the note about the native preview (it becomes the default package), and a link to the new arcadedb-python component (#505).

Today the page is correct for the published wheel (arcadedb-embedded 26.10.2.post1), and arcadedb on PyPI is still a 0.0.1 placeholder, so I cannot run the two samples against the new packages yet. I will push the branch update when the first 26.11.1 pre-release is on PyPI and the samples have been re-run. If you would rather merge the page as it is now, that is fine; the rename would then be a small follow-up PR.