chore(packages): remove contrib/bencode and update references (T8-T10)

- Delete contrib/bencode/ directory (crate migrated to torrust/torrust-bittorrent)
- AGENTS.md: remove bencode from contrib/ description and package table
- docs/packages.md: update contrib/ tree to note migration
- docs/release_process.md: remove torrust-tracker-contrib-bencode from publish checklist
- src/console/ci/qbittorrent_e2e/bencode.rs: update crate name reference in doc comment
- .github/skills/release-new-version/SKILL.md: remove contrib/bencode version bump step
  and torrust-tracker-contrib-bencode from deployment checklist

Part of #1881 (T8, T9, T10)

Author: josecelano

.github/skills/dev/git-workflow/release-new-version/SKILL.md

@@ -67,7 +67,6 @@ Edit `version` in:
 - `Cargo.toml` (workspace)
 - All packages under `packages/` that publish crates
 - `console/tracker-client/Cargo.toml`
-- `contrib/bencode/Cargo.toml`
 
 Also update any internal path dependency `version` constraints.
 
@@ -100,7 +99,6 @@ Check the
 [deployment workflow](https://github.com/torrust/torrust-tracker/actions/workflows/deployment.yaml)
 ran successfully and the following crates were published:
 
-- `torrust-tracker-contrib-bencode`
 - `torrust-located-error`
 - `torrust-tracker-primitives`
 - `torrust-clock`

AGENTS.md

@@ -41,7 +41,7 @@ native IPv4/IPv6 support, private/whitelisted mode, and a management REST API.
 - `src/console/` — Console entry points
 - `packages/` — Cargo workspace packages (all domain logic lives here; see package catalog below)
 - `console/` — Console tools (e.g., `tracker-client`)
-- `contrib/` — Community-contributed utilities (`bencode`) and developer tooling
+- `contrib/` — Developer tooling
 - `contrib/dev-tools/` — Developer tools: git hooks (`pre-commit.sh`, `pre-push.sh`, `install-git-hooks.sh`),
   container scripts, and init scripts
 - `tests/` — Integration tests (`integration.rs`, `servers/`)
@@ -94,9 +94,9 @@ All packages live under `packages/`. The workspace version is `3.0.0-develop`.
 
 **Community contributions** (under `contrib/`):
 
-| Crate     | Description                     |
-| --------- | ------------------------------- |
-| `bencode` | Bencode encode/decode utilities |
+| Crate | Description                                                                                            |
+| ----- | ------------------------------------------------------------------------------------------------------ |
+| —     | None (bencode migrated to [torrust/torrust-bittorrent](https://github.com/torrust/torrust-bittorrent)) |
 
 ## 🏷️ Package Naming Conventions