Migrate Actions workflows to Gitea

- codeql.yml removed: GitHub-only (uses github/codeql-action/*).
- build.yml + release.yml: runs-on switched to ubuntu-latest (Gitea Cloud
  has no Windows runner). Dalamud staging is now downloaded via curl/unzip
  into $HOME/.xlcore/dalamud/Hooks/dev/, the path the Dalamud SDK 15 uses
  on Linux. Locate-step uses find instead of Get-ChildItem.
- release.yml: softprops/action-gh-release replaced with the Gitea-native
  https://gitea.com/actions/release-action. Auto-injected GITHUB_TOKEN on
  Gitea Actions has Gitea-API scope and is sufficient.
- forge-announce.yml: environment: Webhook removed (Gitea has no
  environments — DISCORD_FORGE_WEBHOOK is a repo-level Actions secret).
  avatar_url and embed url switched from raw.githubusercontent.com /
  github.com to gitea.com.
- release-footer.md: install URL plus the five doc links (README, PRIVACY,
  THIRD_PARTY_NOTICES, SECURITY, SUPPORT) and LICENSE link switched to
  gitea.com/.../src/branch/main/. ChatTwo upstream link stays on GitHub.

.github/release-footer.md

@@ -8,19 +8,19 @@ Dalamud main plugin repo. To install:
 
 1. In XIVLauncher: **Settings → Experimental → Custom Plugin Repositories**
 2. Add the URL:
-   `https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/repo.json`
+   `https://gitea.com/JonKazama-Hellion/HellionChat/raw/branch/main/repo.json`
 3. Enable, save, then `/xlplugins` → search **Hellion Chat** → install
 
 ## Project documents
 
-- [README](https://github.com/JonKazama-Hellion/HellionChat/blob/main/README.md) — features, architecture, build
-- [Privacy notice](https://github.com/JonKazama-Hellion/HellionChat/blob/main/PRIVACY.md) — what the plugin stores and sends
-- [Third-party notices](https://github.com/JonKazama-Hellion/HellionChat/blob/main/docs/THIRD_PARTY_NOTICES.md) — dependencies and licences
-- [Security policy](https://github.com/JonKazama-Hellion/HellionChat/blob/main/SECURITY.md) — vulnerability reporting
-- [Support](https://github.com/JonKazama-Hellion/HellionChat/blob/main/SUPPORT.md) — bug reports, questions, contact paths
+- [README](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/README.md) — features, architecture, build
+- [Privacy notice](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/PRIVACY.md) — what the plugin stores and sends
+- [Third-party notices](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/docs/THIRD_PARTY_NOTICES.md) — dependencies and licences
+- [Security policy](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/SECURITY.md) — vulnerability reporting
+- [Support](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/SUPPORT.md) — bug reports, questions, contact paths
 
 ## Licence
 
-[EUPL-1.2](https://github.com/JonKazama-Hellion/HellionChat/blob/main/LICENSE).
+[EUPL-1.2](https://gitea.com/JonKazama-Hellion/HellionChat/src/branch/main/LICENSE).
 Based on [Chat 2](https://github.com/Infiziert90/ChatTwo) by Infi and Anna,
 also EUPL-1.2.