docs: fix PAG anchor and the StableDiffusionPipelineSafe row in the SD overview

[simpleqt]

Description: fixes two dead links in the API docs:

1. docs/source/en/api/pipelines/pag.md linked #pagappliedlayers; the heading ### pag_applied_layers keeps its underscores → #pag_applied_layers.
2. docs/source/en/api/pipelines/stable_diffusion/overview.md: the pipelines table linked ./stable_diffusion_safe, a doc page that no longer exists anywhere under docs/source (verified case-sensitively). The row now names the deprecated pipeline as plain text instead of a dead link.

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[github-actions]

Hi @simpleqt, thanks for the PR! It does not appear to link an issue it fixes. If this PR addresses an existing issue, please add a closing keyword (e.g. Fixes #1234) to the PR description so the issue is linked. See the contribution guide for more details. If this PR intentionally does not fix a tracked issue, a maintainer can add the no-issue-needed label to silence this reminder.

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[simpleqt]

Closing — pooled into #14715 combined docs PR to reduce review overhead. All fixes are preserved in the combined branch.

[simpleqt]

Correction: my closing comment pointed to #14715 — that number was wrong. The live pooled PR is #14757 (all fixes preserved there, now rebased onto current main).