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/workflows/forge-announce.yml

@@ -34,10 +34,9 @@ jobs:
   announce:
     name: Post changelog to Hellion Forge
     runs-on: ubuntu-latest
-    # The DISCORD_FORGE_WEBHOOK secret lives under Settings → Environments
-    # → Webhook (case-sensitive). Without this declaration the secret is
-    # not in scope for the job.
-    environment: Webhook
+    # The DISCORD_FORGE_WEBHOOK secret is set as a repo-level Actions Secret
+    # on Gitea (Settings → Actions → Secrets). Repo-level secrets are in
+    # scope for every job by default, no environment: declaration needed.
     timeout-minutes: 5
 
     steps:
@@ -134,7 +133,7 @@ jobs:
           # ---------- Embed-Payload bauen ----------
           $payload = [ordered]@{
               username = "Forge Herald"
-              avatar_url = "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/HellionChat/images/icon.png"
+              avatar_url = "https://gitea.com/JonKazama-Hellion/HellionChat/raw/branch/main/HellionChat/images/icon.png"
               content = "<@&1500489631555260446>"
               allowed_mentions = [ordered]@{
                   parse = @()
@@ -143,7 +142,7 @@ jobs:
               embeds = @(
                   [ordered]@{
                       title = $title
-                      url = "https://github.com/JonKazama-Hellion/HellionChat/releases/tag/$tag"
+                      url = "https://gitea.com/JonKazama-Hellion/HellionChat/releases/tag/$tag"
                       color = 12730636
                       description = $description
                       footer = [ordered]@{ text = $footerText }