fix(review): language-tagged suggestion fence for Gitea syntax highlighting

Gitea 1.26.x has no GitHub-style 'Apply suggestion' button — a ```suggestion
fence is just an unknown-language code block, so chroma does not highlight it
and there is no apply control. Switch inline_comment_body to wrap the suggested
fix in a fence tagged with the file's language (new _lang_for_path helper,
.java→java, .ts→typescript, .py→python, ...), so Gitea syntax-highlights the
code. No capability lost (there was never an apply button on this Gitea
version). Correct the docstrings/skills/README that wrongly claimed an
apply-button was rendered.

Co-Authored-By: Claude <noreply@anthropic.com>

.opencode/agents/pragent.md

@@ -87,8 +87,8 @@ read the full file around a flagged line, not just the diff hunk.
    the POST-CHANGE version of `path` — a context line or an added `+` line shown
    in the diff. Never a removed line. If unsure, use the closest context line you
    can see in the diff. A finding with a bad line gets folded into the summary as
-   a bullet instead of an inline comment, so anchoring correctly is what makes a
-   suggestion apply-able in Gitea.
+   a bullet instead of an inline comment, so anchoring correctly is what gets a
+   finding shown inline with its suggested-fix code block (language-highlighted).
 
 ## Output — REQUIRED exact shape