feat(gateway): skill-aware slash commands, paginated /commands, Telegram 100-cap (#3934)

* feat(gateway): skill-aware slash commands, paginated /commands, Telegram 100-cap

Map active skills to Telegram's slash command menu so users can
discover and invoke skills directly. Three changes:

1. Telegram menu now includes active skill commands alongside built-in
   commands, capped at 100 entries (Telegram Bot API limit). Overflow
   commands remain callable but hidden from the picker. Logged at
   startup when cap is hit.

2. New /commands [page] gateway command for paginated browsing of all
   commands + skills. /help now shows first 10 skill commands and
   points to /commands for the full list.

3. When a user types a slash command that matches a disabled or
   uninstalled skill, they get actionable guidance:
   - Disabled: 'Enable it with: hermes skills config'
   - Optional (not installed): 'Install with: hermes skills install official/<path>'

Built on ideas from PR #3921 by @kshitijk4poor.

* chore: move 21 niche skills to optional-skills

Move specialized/niche skills from built-in (skills/) to optional
(optional-skills/) to reduce the default skill count. Users can
install them with: hermes skills install official/<category>/<name>

Moved skills (21):
- mlops: accelerate, chroma, faiss, flash-attention,
  hermes-atropos-environments, huggingface-tokenizers, instructor,
  lambda-labs, llava, nemo-curator, pinecone, pytorch-lightning,
  qdrant, saelens, simpo, slime, tensorrt-llm, torchtitan
- research: domain-intel, duckduckgo-search
- devops: inference-sh cli

Built-in skills: 96 → 75
Optional skills: 22 → 43

* fix: only include repo built-in skills in Telegram menu, not user-installed

User-installed skills (from hub or manually added) stay accessible via
/skills and by typing the command directly, but don't get registered
in the Telegram slash command picker. Only skills whose SKILL.md is
under the repo's skills/ directory are included in the menu.

This keeps the Telegram menu focused on the curated built-in set while
user-installed skills remain discoverable through /skills and /commands.

optional-skills/devops/cli/references/app-discovery.md

@@ -0,0 +1,112 @@
+# Discovering Apps
+
+## List All Apps
+
+```bash
+infsh app list
+```
+
+## Pagination
+
+```bash
+infsh app list --page 2
+```
+
+## Filter by Category
+
+```bash
+infsh app list --category image
+infsh app list --category video
+infsh app list --category audio
+infsh app list --category text
+infsh app list --category other
+```
+
+## Search
+
+```bash
+infsh app search "flux"
+infsh app search "video generation"
+infsh app search "tts" -l
+infsh app search "image" --category image
+```
+
+Or use the flag form:
+
+```bash
+infsh app list --search "flux"
+infsh app list --search "video generation"
+infsh app list --search "tts"
+```
+
+## Featured Apps
+
+```bash
+infsh app list --featured
+```
+
+## Newest First
+
+```bash
+infsh app list --new
+```
+
+## Detailed View
+
+```bash
+infsh app list -l
+```
+
+Shows table with app name, category, description, and featured status.
+
+## Save to File
+
+```bash
+infsh app list --save apps.json
+```
+
+## Your Apps
+
+List apps you've deployed:
+
+```bash
+infsh app my
+infsh app my -l  # detailed
+```
+
+## Get App Details
+
+```bash
+infsh app get falai/flux-dev-lora
+infsh app get falai/flux-dev-lora --json
+```
+
+Shows full app info including input/output schema.
+
+## Popular Apps by Category
+
+### Image Generation
+- `falai/flux-dev-lora` - FLUX.2 Dev (high quality)
+- `falai/flux-2-klein-lora` - FLUX.2 Klein (fastest)
+- `infsh/sdxl` - Stable Diffusion XL
+- `google/gemini-3-pro-image-preview` - Gemini 3 Pro
+- `xai/grok-imagine-image` - Grok image generation
+
+### Video Generation
+- `google/veo-3-1-fast` - Veo 3.1 Fast
+- `google/veo-3` - Veo 3
+- `bytedance/seedance-1-5-pro` - Seedance 1.5 Pro
+- `infsh/ltx-video-2` - LTX Video 2 (with audio)
+- `bytedance/omnihuman-1-5` - OmniHuman avatar
+
+### Audio
+- `infsh/dia-tts` - Conversational TTS
+- `infsh/kokoro-tts` - Kokoro TTS
+- `infsh/fast-whisper-large-v3` - Fast transcription
+- `infsh/diffrythm` - Music generation
+
+## Documentation
+
+- [Browsing the Grid](https://inference.sh/docs/apps/browsing-grid) - Visual app browsing
+- [Apps Overview](https://inference.sh/docs/apps/overview) - Understanding apps
+- [Running Apps](https://inference.sh/docs/apps/running) - How to run apps