Extract review logic into bot_actions module

Move `exec_review`, `download_git_diff`, and review formatting
to a new `bot_actions::review` module. Update the review flow to
post inline review comments via the Gitea API and simplify the
comment markdown to a summary. Add diff formatting that
preprocesses added lines with line numbers for the LLM prompt.

src/consts.rs

@@ -17,19 +17,14 @@ pub const REVIEW_PROMPT: &str = "
 
     This is the user comment: \"{comment}\"
 
-    This is the git diff of the code changes:
+    The code changes (only added lines, with line numbers):
 
-    \"{diff}\"
+    {diff}
 
     Please review the code changes and provide feedback.
 
-    IMPORTANT — How to compute the line number:
-    The diff is in unified format. Each hunk starts with a header like:
-    `@@ -old_start,old_count +new_start,new_count @@`
-    The `line` field must be the line number in the **new** version of the file.
-    To find it, start at `new_start`, then count every context line (no prefix)
-    and every added line (prefixed with `+`) — skip removed lines (prefixed with `-`).
-    The line number increments by 1 for each context or added line.
+    IMPORTANT: the `line` field must be the line number shown before each line.
+    The provided code has the format: `filename:line:code`
 
     Return your feedback, in french, with only this json format, reviews must contain each review
     All fields are mandatory.