feat(gitea): add gitea-files skill

Covers get_file_contents, get_dir_contents, get_repository_tree,
create_or_update_file, delete_file — all verified working with the
current write:issue/write:repository token scope.

plugins/gitea/skills/gitea-files/references/sources.md

@@ -0,0 +1,36 @@
+# Sources
+
+## gitea-mcp-repo
+
+**Description:** Official gitea-mcp repository (v1.3.0); operation/*.go source files documenting all 55 MCP tools, their parameters, and CLI flags.
+
+**Source:** https://gitea.com/gitea/gitea-mcp
+
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+
+**Contributing files:**
+- SKILL.md (Gotchas, Reading, Writing — tool parameters and SHA/concurrency behavior, cross-checked live against the deployed MCP tool schemas via ToolSearch)
+- references/examples.md (canonical call sequences)
+
+## gitea-mcp-slim-go
+
+**Description:** Slim response shape structs from gitea-mcp source; defines exactly which fields the MCP server returns for files (top-level `sha`, no nested `content.sha`) and directory/tree entries.
+
+**Source:** https://gitea.com/gitea/gitea-mcp/raw/branch/main/operation/repo/slim.go
+
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+
+**Contributing files:**
+- SKILL.md (Gotchas — top-level `sha` field location, `get_dir_contents`/`get_repository_tree` not being usable SHA sources for a file write)
+- references/examples.md (SHA-first update/delete sequences)
+
+## context7-websites-gitea
+
+**Description:** Official Gitea docs mirror on Context7 (docs.gitea.com content) — confirms direct-commit file editing through the web UI is a first-class, expected workflow rather than an API-only escape hatch.
+
+**Source:** context7:/websites/gitea
+
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+
+**Contributing files:**
+- SKILL.md (Gotchas — "Direct commits to a branch are a first-class action, not a workaround")