Complete the Pattern matching section with deconstruction coverage and the introductory tutorial

[Everyday C# PR 21 — Pattern matching: deconstruction + tutorial](https://github.com/dotnet/docs/blob/EverydayCSharp/.github/projects/everyday-csharp/plan/phase-f-patterns-functional.md#pr-21--pattern-matching-deconstruction--tutorial)

PR 21 is the committed clean boundary that fully completes Pattern matching (§11). Once the overview/basic-pattern and advanced-pattern-form work is live, this closes the remaining core article gap and moves the introductory tutorial into Fundamentals, without pulling the optional Functional techniques tutorial into September's scope.

Revise `deconstruct.md` to cover records, tuples, custom `Deconstruct`, and mixed deconstructions at Fundamentals level. Pull `tutorials/patterns-objects.md` into `fundamentals/tutorials/pattern-matching.md`, updating snippets, `toc.yml`, and redirects (including the former `functional/deconstruct.md` path). Leave the advanced data-driven pattern tutorial where it is unless implementation finds a safe, already-planned move.

Done when §11 has no remaining planned core gaps, deconstruction coverage is coherent with tuples/records/custom Deconstruct/Discards, the tutorial is adapted with redirects, and no former `functional/` deconstruction path breaks. See the [Phase F plan](https://github.com/dotnet/docs/blob/main/.github/projects/everyday-csharp/plan/phase-f-patterns-functional.md) for scope.

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[Associated WorkItem - 632370](https://dev.azure.com/msft-skilling/Content/_workitems/edit/632370)