docs: clarify provider-neutral setup and authentication guidance

[Hou (SciencePotato)]

Summary

Audit customer documentation for unintended provider preference while retaining accurate provider-specific requirements.

• Replace the named provider in reusable setup templates with an explicit customer choice; no provider is implied as the default or healthy selection.
• Present the provider support table alphabetically, with equal access to each guided authentication walkthrough.
• Correct the three runtime guides so general credential instructions cover both API-key and OAuth onboarding.
• Include every bundled API-key adapter in shared authentication-setting references without implying all adapters have guided setup support.
• Add neutral navigation to the provider-specific contracts and label the existing wire example as a provider-specific example, not a ranking.

The main README remains provider-neutral. Exact secret names, OAuth settings, supported profiles, and meaningful differences remain documented. No runtime, catalogs, defaults, or screenshots changed.

Audit scope

Read all 13 tracked Markdown documents, shared settings, setup help, provider catalog/profiles, and adapter authentication declarations. Visually inspected all 14 embedded PNGs, including architecture diagrams and onboarding screenshots.

The Security Store cards retain their existing non-endorsement caption. Logos, offer titles and badges are source offer content; the cards do not imply guided support for every listed provider. Credential screenshots retain exact-name and example-only caveats. No equal-feature, commercial, or certification claims were introduced.

Verification

• All 343 local targets, 142 Markdown anchor references and 14 image references resolve; existing edited-file anchors are preserved.
• Modified PowerShell templates parse for each supported guided provider, and named parameters match the setup entry point. Snippets were not executed.
• Shared settings JSON parses with string-valued settings. git diff --check passes.
• External URLs checked structurally only; no live Azure, provider or portal operations performed.

Based on main 9b3d299, including the latest onboarding and endpoint configuration changes. Seven Markdown files changed; no runtime tests required for this documentation-only change.