feat(gitea): add gitea-issues skill

Covers list_issues, issue_read, issue_write, and search_issues, closing out
all four enrichments deferred from issue #6 comment #848: label inference
(delegated to gitea-labels-milestones), milestone assignment on create,
an assignee workaround for the blocked get_me/read:user scope, and the
"Depends on #N" dependency-linking convention validated by Gitea's
automatic cross-reference rendering.

Call signatures were re-verified live via ToolSearch against the deployed
gitea-mcp server rather than copied from api-reference.md, per ADR 0011 --
this caught that list_issues has no `type` or `milestones` parameter on the
live schema, despite the research doc documenting both (the exact drift
that caused issue #6 comment #849).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FNJWdVvdgvZCHi1hZGqgVQ

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

@@ -0,0 +1,41 @@
+# Sources
+
+**Note on call signatures:** per `docs/adr/0011-gitea-skill-deep-modules.md`, the tool parameter
+signatures in `references/issues.md` and `references/search.md` were re-verified live via
+`ToolSearch` against the deployed `gitea-mcp` server at authoring time — they are not copied
+verbatim from `api-reference.md`. This resolves issue #6 comment #849's root-cause finding that a
+prior skill was authored from API docs that had drifted from the actual MCP tool schema; the live
+check caught exactly this drift on `list_issues` (see SKILL.md Gotchas — the research doc documents
+a `type` and a `milestones` parameter that do not exist on the deployed server).
+
+## gitea-mcp-repo
+
+- **URL:** https://gitea.com/gitea/gitea-mcp
+- **Description:** Official gitea-mcp repository (v1.3.0); operation/*.go source files documenting all 55 MCP tools, their parameters, and CLI flags.
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** SKILL.md, references/issues.md, references/search.md, references/enrichments.md
+- **Status:** `extracted`
+
+## gitea-mcp-slim-go
+
+- **URL:** https://gitea.com/gitea/gitea-mcp/raw/branch/main/operation/issue/slim.go
+- **Description:** Slim response shape structs from gitea-mcp source; defines exactly which fields the MCP server returns for issues (label name-vs-ID slimming, milestone object-vs-string shape, `is_pull` presence on single-item reads only).
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** SKILL.md, references/issues.md
+- **Status:** `extracted`
+
+## context7-websites-gitea
+
+- **URL:** context7:/websites/gitea
+- **Description:** Official Gitea docs mirror on Context7 (docs.gitea.com content) — backs the automatic cross-reference rendering (`#N`/`!N`) that validates the "Depends on #N" dependency-linking convention.
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** references/enrichments.md
+- **Status:** `extracted`
+
+## context7-gitea-tea-cli
+
+- **URL:** context7:/git_gitea_com/gitea_tea
+- **Description:** Official `tea` CLI (reference Gitea client) docs on Context7 — practitioner command patterns for issues, PRs, and releases. Consulted alongside context7-websites-gitea while researching `workflow-conventions.md`'s cross-reference-linking section (both sources contribute to that research doc); its issue-specific command patterns did not end up informing any gitea-issues content beyond what context7-websites-gitea already backs.
+- **Research doc:** plugins/gitea/docs/research/docs/gitea/sources.md
+- **Contributing files:** (none)
+- **Status:** `extracted`