feat: Phase 3c — dose logging + adherence, profile management, tests

Three workstreams, all backend+frontend (per scope decisions):

Dose logging + real adherence (backend + frontend):
* log_dose now returns the created dose (201 + body) instead of an empty 201.
* get_adherence implemented for real: queries the medication_doses collection
  over the last 30 days, counts taken vs total, computes the rate. The previous
  implementation hardcoded zeros. Removed the dead calculate_adherence stub.
* Frontend: fixed DoseLog type to match backend MedicationDose (taken:bool,
  loggedAt, camelCase); added AdherenceStats + LogDoseRequest types; logDose() +
  getAdherence() in api.ts; loadAdherence/logDose actions in the medication
  store (adherence cache keyed by med id); new DoseLogger component (Taken/
  Skipped buttons + LinearProgress adherence bar) embedded in each
  MedicationManager card.

Profile management (backend + frontend):
* New GET/PUT /api/profiles/me endpoints (ProfileResponse excludes encryption
  fields; find_by_user_id + update_name on ProfileRepository).
* Register auto-creates a default 'patient' profile (deterministic profile_id =
  profile_<user_id>) — this is the contract the frontend relies on.
* Frontend: Profile type; getProfile()/updateProfileName() in api.ts; useProfileStore;
  new ProfileEditor component (view/edit name, shows role) as a 4th Dashboard tab.
* Resolved the MedicationManager profile_id TODO: now derives profile_<user_id>
  instead of the 'default' fallback.
* NOTE: profile name is stored plaintext (the model anticipates encryption via
  nameIv/nameAuthTag but no crypto layer is implemented yet — TODO).

Vitest tests:
* Added @testing-library/user-event; setupTests clears localStorage + cleanup
  between tests; new test/mockStore.ts helper (mocks the co-located stores,
  handles both selector and no-selector call patterns).
* 5 test files, 20 tests: SeverityChip (4), useMedicationStore actions incl.
  loadMedications/createMedication/logDose (4), MedicationManager render+dialog
  (5), InteractionsChecker selection+results (4), HealthStats table+dialog (3).

Verified: backend cargo fmt/build/clippy 0 warnings, 19 unit tests pass;
frontend npm build clean, 20 vitest tests pass. Solaria round-trip confirmed:
profile auto-created on register (GET /profiles/me), PUT updates name, dose log
returns the dose body, adherence computes 66.7% for 2-taken/1-skipped.

KNOWN FOLLOW-UP (separate task): the backend Medication list response is deeply
nested + camelCase + stores fields inside medicationData.data; the frontend
Medication type assumes flat top-level snake_case fields. This pre-dates Phase 3c
and affects the whole MedicationManager — needs a backend serialization fix or a
frontend adapter.

backend/src/models/profile.rs

@@ -52,4 +52,33 @@ impl ProfileRepository {
             .find_one(doc! { "profileId": profile_id }, None)
             .await
     }
+
+    /// Look up a profile by its owning user id.
+    pub async fn find_by_user_id(&self, user_id: &str) -> mongodb::error::Result<Option<Profile>> {
+        self.collection
+            .find_one(doc! { "userId": user_id }, None)
+            .await
+    }
+
+    /// Update the profile's display name. NOTE: name is currently stored
+    /// plaintext — the model's nameIv/nameAuthTag fields anticipate encryption
+    /// that isn't implemented yet (TODO).
+    pub async fn update_name(
+        &self,
+        user_id: &str,
+        name: &str,
+    ) -> mongodb::error::Result<Option<Profile>> {
+        self.collection
+            .find_one_and_update(
+                doc! { "userId": user_id },
+                doc! { "$set": {
+                    "name": name,
+                    "nameIv": "",
+                    "nameAuthTag": "",
+                    "updatedAt": DateTime::now()
+                }},
+                None,
+            )
+            .await
+    }
 }