docs: pool eight small doc fixes into one PR (#14757)

* docs: fix latent -> latents in LTX latent upsampler docstrings

__call__ takes 'latents' (the docstring said 'latent', and its own
description says 'Input latents to normalize').

* docs: fix 'promt' typo in kandinsky5 default prompt templates

The default system template sent to the Qwen text encoder misspelled
'prompt engineer' as 'promt engineer' (4 pipelines).

Note: this changes the token sequence of the default template, so
default outputs will differ numerically from before / from the
upstream Kandinsky5 reference. If exact parity with the reference
repo is preferred, the reference itself would need the same fix.

* docs: fix docstring parameter names that do not match signatures

- flux controlnet encode_prompt documented a clip_skip parameter that
  does not exist (copy-paste from SD-style docs; flux has no CLIP
  layer-skipping)
- hunyuan_video1_5 pipelines documented num_images_per_prompt while
  the parameter is num_videos_per_prompt
- kandinsky5 _encode_prompt_qwen/_encode_prompt_clip documented
  num_videos_per_prompt, which neither method accepts

* docs(zh): fix English anchors pointing at translated Chinese headings

speed-memory-optims.md linked ./memory#model-offloading and
#group-offloading while the zh memory page translates those headings
(模型卸载 / 组卸载); using_peft_for_inference.md linked #hotswapping
while the zh heading is 热切换. Repointed at the Chinese slugs.

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

- pag.md linked #pagappliedlayers; the heading '### pag_applied_layers'
  keeps its underscores (#pag_applied_layers)
- the SD overview table linked ./stable_diffusion_safe, a doc page that
  no longer exists anywhere under docs/source; the row now names the
  deprecated pipeline as plain text instead of a dead link

* docs: fix dead Masked Im2Im TOC anchors in community pipelines README

The TOC rows linked #stable-diffusion-masked-im2im /
#stable-diffusion-xl-masked-im2im; the actual headings are
'Masked Im2Im Stable Diffusion Pipeline' and 'Masked Im2Im Stable
Diffusion Pipeline XL' (lines 3184/3219).

* docs(examples): drop duplicated 'with' in T5/Gemma sequence-length help strings

16 example scripts' --max_sequence_length help read 'to use with with
the T5 text encoder' (or the Gemma variant); surfaced in --help output.

* fix(links): keep the pag_applied_layers anchor in doc-builder form

doc-builder slugifies headings by dropping underscores, so the heading
'### pag_applied_layers' anchors as #pagappliedlayers — the form the
check-links CI expects. GitHub-style underscores broke it.

Signed-off-by: simpleqt <89645338+simpleqt@users.noreply.github.com>

* fix(kandinsky5): recompute prompt_template_encode_start_idx after the promt fix

Correcting 'promt' -> 'prompt' in the system templates shifts each
template's token count by one (verified with the Qwen2.5-VL tokenizer:
41->40, 55->54, 129->128, 129->128). Without this, the hardcoded start
indices slice the encoded prompt one token off.

---------

Signed-off-by: simpleqt <89645338+simpleqt@users.noreply.github.com>