Document intentional error suppressions with comments (gt-zn9m)

All 156 instances of _ = error suppression in non-test code now have
explanatory comments documenting why the error is intentionally ignored.

Categories of intentional suppressions:
- non-fatal: session works without these - tmux environment setup
- non-fatal: theming failure does not affect operation - visual styling
- best-effort cleanup - defer cleanup on failure paths
- best-effort notification - mail/notifications that should not block
- best-effort interrupt - graceful shutdown attempts
- crypto/rand.Read only fails on broken system - random ID generation
- output errors non-actionable - fmt.Fprint to io.Writer

This addresses the silent failure and debugging concerns raised in the
issue by making the intentionality explicit in the code.

Generated with Claude Code https://claude.com/claude-code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/doctor/types.go

@@ -140,12 +140,12 @@ func (r *Report) Print(w io.Writer, verbose bool) {
 		r.printCheck(w, check, verbose)
 	}
 
-	// Print summary
+	// Print summary (output errors non-actionable)
 	_, _ = fmt.Fprintln(w)
 	r.printSummary(w)
 }
 
-// printCheck outputs a single check result.
+// printCheck outputs a single check result (output errors non-actionable).
 func (r *Report) printCheck(w io.Writer, check *CheckResult, verbose bool) {
 	var prefix string
 	switch check.Status {
@@ -172,7 +172,7 @@ func (r *Report) printCheck(w io.Writer, check *CheckResult, verbose bool) {
 	}
 }
 
-// printSummary outputs the summary line.
+// printSummary outputs the summary line (output errors non-actionable).
 func (r *Report) printSummary(w io.Writer) {
 	parts := []string{
 		fmt.Sprintf("%d checks", r.Summary.Total),