style(core): apply cargo fmt across routes, services, models, tests

Pure rustfmt reflow (import grouping, array/match-arm/call-arg wrapping,
alphabetized module decls, comment realignment). No semantic change:
full-diff and `git diff -w` both confirm logic byte-identical to 271c363;
workspace builds and all 74 core tests pass. Retained pre-existing WIP
brought forward after verification.

src/models/profile.rs

@@ -38,16 +38,16 @@ pub struct CreateProfileRequest {
 /// XP required to reach each level (cumulative total from level 1).
 /// Level 1 starts at 0 XP. Level 2 needs 500 total XP, etc.
 pub const XP_THRESHOLDS: &[i64] = &[
-    0,      // level 1
-    500,    // level 2
-    1200,   // level 3
-    2000,   // level 4
-    3000,   // level 5
-    4200,   // level 6
-    5600,   // level 7
-    7200,   // level 8
-    9000,   // level 9
-    11000,  // level 10
+    0,     // level 1
+    500,   // level 2
+    1200,  // level 3
+    2000,  // level 4
+    3000,  // level 5
+    4200,  // level 6
+    5600,  // level 7
+    7200,  // level 8
+    9000,  // level 9
+    11000, // level 10
 ];
 
 /// Compute the level for a given cumulative XP total.
@@ -75,7 +75,7 @@ pub fn coins_for_level(new_level: i64) -> i64 {
 /// Pack granted at milestone levels (5, 10, 15, 20, …).
 pub fn pack_for_level(new_level: i64) -> Option<&'static str> {
     match new_level {
-        5  => Some("bronze_pack"),
+        5 => Some("bronze_pack"),
         10 => Some("silver_pack"),
         15 => Some("gold_pack"),
         20 => Some("rare_gold_pack"),