feat(yt-dlp): add wrapper with embedding + SponsorBlock defaults

Add functions/yt-dlp.fish, shadowing yt-dlp to prepend sane defaults
(--sponsorblock-remove all, --embed-subs, --embed-metadata,
--embed-thumbnail). Each default is suppressed when the user already
passes that flag, its alias (--add-metadata), its negation
(--no-embed-thumbnail), the --opt=value form (--sponsorblock-remove=...),
or the global --no-sponsorblock kill. User args pass through last so an
explicit flag wins on precedence. Gated as a C1 opinionated alias;
falls back to bare `command yt-dlp` when disabled.

Register yt-dlp as a recommended (rec tier) dependency in the fish-deps
catalog and document the function (§5.13) and dependency in the SSOT
and index.

docs/fish-config.md

@@ -923,7 +923,7 @@ Add -i (interactive confirmation) to destructive commands:
       Integrations  wakatime, tailscale
       Recommended   cargo, starship, uv, direnv, paru, yay, eza, lsd, bat,
                     btop, dust, duf, prettyping, ov, ripgrep, lazygit,
-                    lazydocker, trash, kitty, wezterm, python3
+                    lazydocker, trash, kitty, wezterm, python3, yt-dlp
 
     fish-deps
     fish-deps install
@@ -1277,6 +1277,21 @@ Add -i (interactive confirmation) to destructive commands:
     spark 1 1 2 5 14 42
     echo "3 7 2 9 1" | spark
 
+### yt-dlp
+
+    Synopsis:  yt-dlp [args...] URL [URL...]
+    Wraps yt-dlp, prepending sane defaults: --sponsorblock-remove all,
+    --embed-subs, --embed-metadata, and --embed-thumbnail. Each default
+    is suppressed when you already pass that flag, its alias, or its
+    negation (e.g. --no-embed-thumbnail drops the thumbnail default;
+    --no-sponsorblock or your own --sponsorblock-remove drops ours). All
+    other arguments pass through unchanged, and --help falls through to
+    real yt-dlp. Opinionated component (C1 aliases); when disabled it
+    passes straight through to the system yt-dlp.
+
+    yt-dlp dQw4w9WgXcQ
+    yt-dlp --no-embed-thumbnail dQw4w9WgXcQ
+
 ---
 
 ## 5.14 Miscellaneous
@@ -1522,6 +1537,9 @@ fish-deps manages these tools. Run `fish-deps` to check status, or
                 Note: uv does not provide python3 on PATH, and Arch's base
                 does not include it, so it is listed separately. All
                 consumers degrade gracefully without it.
+    yt-dlp      Video/media downloader; backs the yt-dlp wrapper function.
+                Optional — the wrapper falls back to the system yt-dlp and
+                the rest of the config works without it.
 
 ## Install Methods