fix: Replace fmt.eprint calls with logs.

frontmatter.odin

@@ -1,7 +1,7 @@
 package main
 
 import "core:encoding/json"
-import "core:fmt"
+import "core:log"
 import "core:strings"
 
 Frontmatter :: struct {
@@ -38,7 +38,7 @@ parse_frontmatter :: proc(content: string) -> (fm: Frontmatter, body: string, ok
 
 	value, err := json.parse_string(json_str, spec = .JSON)
 	if err != nil {
-		fmt.eprintfln("failed to parse frontmatter JSON: %v", err)
+		log.errorf("failed to parse frontmatter JSON: %v", err)
 		return
 	}
 	defer json.destroy_value(value)

main.odin

@@ -20,7 +20,7 @@ main :: proc() {
 	when SPALL {
 		ctx, ok := spall.context_create_with_scale("thor.spall", false, 1.0)
 		if !ok {
-			fmt.eprintln("Failed to create spall trace file")
+			log.fatal("Failed to create spall trace file")
 			os.exit(1)
 		}
 		spall_ctx = ctx

render.odin

@@ -397,7 +397,7 @@ write_page :: proc(output_dir: string, permalink: string, html: string) {
 
 	dir := fmt.tprintf("%s/%s", output_dir, rel)
 	if err := os.make_directory_all(dir); err != nil && err != .Exist {
-		fmt.eprintfln("cannot create %s: %v", dir, err)
+		log.errorf("cannot create %s: %v", dir, err)
 		return
 	}
 
@@ -407,7 +407,7 @@ write_page :: proc(output_dir: string, permalink: string, html: string) {
 
 write_file :: proc(path: string, html: string) {
 	if err := os.write_entire_file_from_string(path, html); err != nil {
-		fmt.eprintfln("cannot write %s: %v", path, err)
+		log.errorf("cannot write %s: %v", path, err)
 	}
 }