fix: address self-review findings on PR #90

- Remove unused error return from BuildPositionToLineMap (always nil)
- Add comment explaining intentional CommitID drop in PostReview
- Refactor TestAdapter_PostReview_WithComments to route by URL path
- Add TestAdapter_GetFileContent_RefRouting test
- Acknowledge maxPosition O(n) with code comment
- Remove redundant TestAdapter_CompileTimeCheck (compile-time var _ exists)
- Fix GetPullRequestFiles comment (Patch field is omitted, not 'set to empty')
- Acknowledge translateEvent fallback as intentional design

gitea/position.go

@@ -53,6 +53,7 @@ func (pm *PositionMap) Translate(file string, position int) (int, error) {
 }
 
 // maxPosition returns the highest position number for a file.
+// O(n) per call — acceptable since deletion-line fallback is rare and n is small (typical hunk size).
 func (pm *PositionMap) maxPosition(file string) int {
 	max := 0
 	for pos := range pm.files[file] {
@@ -72,7 +73,7 @@ func (pm *PositionMap) maxPosition(file string) int {
 //   - A new @@ hunk within the same file continues incrementing (does not reset)
 //   - Position maps to the new file line number for additions and context lines
 //   - Deletion lines have a position but no new-file line number (stored as -1)
-func BuildPositionToLineMap(diff string) (*PositionMap, error) {
+func BuildPositionToLineMap(diff string) *PositionMap {
 	pm := &PositionMap{files: make(map[string]map[int]int)}
 
 	lines := strings.Split(diff, "\n")
@@ -153,7 +154,7 @@ func BuildPositionToLineMap(diff string) (*PositionMap, error) {
 		}
 	}
 
-	return pm, nil
+	return pm
 }
 
 // parseHunkStart extracts the new-file starting line number from a hunk header.