fix(gitea): add missing gotchas to gitea-files docs

A documentation-accuracy audit against research docs found three gotchas
in troubleshooting.md that were dropped from gitea-files/SKILL.md during
original authoring: signed-commit branch protection silently blocking
file writes (a distinct failure mode from stale-SHA that an agent could
otherwise misdiagnose and retry indefinitely), reverse-proxy 413s on
large base64-encoded write payloads, and 404-vs-403 scope masking on the
read tools. Also adds the context7-gitea-tea-cli provenance entry to
references/sources.md (Contributing files: none) to resolve a
pre-existing skill-audit provenance FAIL surfaced while validating this
change, matching the pattern already used by sibling skills.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VwtxcDXuLZxYzWnT2FaoZU

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

@@ -34,3 +34,13 @@
 
 **Contributing files:**
 - SKILL.md (Gotchas — "Direct commits to a branch are a first-class action, not a workaround")
+
+## context7-gitea-tea-cli
+
+**Description:** Official `tea` CLI (reference Gitea client) docs on Context7 — practitioner command patterns for issues, PRs, and releases, including semver tag/release conventions, draft/prerelease flags, and release-notes-from-file conventions. Consulted alongside `context7-websites-gitea` while researching `workflow-conventions.md` (both sources contribute to that research doc, backing `gitea-workflow`); its file-command patterns did not end up informing any gitea-files content.
+
+**Source:** context7:/git_gitea_com/gitea_tea
+
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+
+**Contributing files:** (none)