Trim tool schemas, add param aliases, new PR methods (#191)

- Tool list size reduced by 26.6% (43,032 → 31,599 bytes on the `tools/list` JSON-RPC response).
- Trim redundant tool/param descriptions; shared description constants for `owner`/`repo`/`page`/`per_page`.
- Schemas now use github-mcp-server param names directly: `issue_number` (was `index` on issue tools), `pull_number` (was `index` on PR tools), `path` (was `filePath`), `query` (was `keyword` on user/repo search), `per_page` (was `perPage`).
- New PR read methods `get_files` and `get_status`; new PR write method `update_branch` (update PR branch from base).
- `list_org_repos` now uses `per_page` (was `pageSize`).
- `milestone_write` accepts `update` and `edit`.
- `create_branch` `old_branch` is optional; Gitea defaults to the repo default branch.
- Fix `list_commits` handler to honour optional `page`/`per_page` schema (was erroring out when callers omitted them).

---
This PR was written with the help of Claude Opus 4.7

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/191
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

operation/packages/packages_test.go

@@ -94,10 +94,10 @@ func TestPackageReadList(t *testing.T) {
 	t.Run("with pagination", func(t *testing.T) {
 		req := mcp.CallToolRequest{}
 		req.Params.Arguments = map[string]any{
-			"method":  "list",
-			"owner":   "test-org",
-			"page":    float64(2),
-			"perPage": float64(10),
+			"method":   "list",
+			"owner":    "test-org",
+			"page":     float64(2),
+			"per_page": float64(10),
 		}
 
 		_, err := packageReadFn(ctx, req)