feat(stores): add Pinia domain stores and update docs

Implement concrete Pinia stores for app UI and domain data instead of
placeholder re-exports, including seeded student records and snackbar state.

Refresh README guidance for components, plugins, and services to document the
current project structure, data flow, and usage conventions.feat(stores): add Pinia domain stores and update docs

Implement concrete Pinia stores for app UI and domain data instead of
placeholder re-exports, including seeded student records and snackbar state.

Refresh README guidance for components, plugins, and services to document the
current project structure, data flow, and usage conventions.

src/stores/semesters.ts

@@ -1 +1,157 @@
-export * from './stores/semesters'
+import { defineStore } from 'pinia'
+import { ref } from 'vue'
+
+export interface CourseRecord {
+  code: string
+  name: string
+  credits: number
+  score: number
+}
+
+export interface SemesterRecord {
+  id: number
+  studentId: number
+  semesterName: string
+  courses: CourseRecord[]
+  rank: number
+  average: number
+}
+
+const seedSemesters: SemesterRecord[] = []
+
+const randomScore = (min = 60, max = 99) => Math.floor(Math.random() * (max - min + 1)) + min
+
+export function generateMockSemesters(studentId: number) {
+  const semesters = [
+    { name: '111 學年度第 1 學期', baseId: 1000 },
+    { name: '111 學年度第 2 學期', baseId: 2000 },
+    { name: '112 學年度第 1 學期', baseId: 3000 },
+    { name: '112 學年度第 2 學期', baseId: 4000 },
+    { name: '113 學年度第 1 學期', baseId: 5000 },
+    { name: '113 學年度第 2 學期', baseId: 6000 },
+  ]
+
+  const subjects = [
+    { name: '資料結構', credits: 3 },
+    { name: '演算法', credits: 3 },
+    { name: '作業系統', credits: 3 },
+    { name: '計算機組織', credits: 3 },
+    { name: '線性代數', credits: 3 },
+    { name: '機率與統計', credits: 3 },
+    { name: '資料庫系統', credits: 3 },
+    { name: '人工智慧導論', credits: 3 },
+    { name: '網頁程式設計', credits: 3 },
+    { name: '計算機網路', credits: 3 },
+  ]
+
+  const count = 5 + (studentId % 2)
+  const result: SemesterRecord[] = []
+
+  for (let i = 0; i < count; i++) {
+    const sem = semesters[i]
+    if (!sem) continue
+    const courseCount = 8 + (studentId % 3)
+    const courses: CourseRecord[] = []
+    const usedSubjects = new Set<number>()
+
+    let totalScore = 0
+    let totalCredits = 0
+
+    while (courses.length < courseCount) {
+      const idx = Math.floor(Math.random() * subjects.length)
+      if (usedSubjects.has(idx)) continue
+      usedSubjects.add(idx)
+
+      const score = randomScore()
+      const subject = subjects[idx]
+      if (!subject) continue
+
+      courses.push({
+        code: `CS${1000 + idx}`,
+        name: subject.name,
+        credits: subject.credits,
+        score,
+      })
+
+      totalScore += score * subject.credits
+      totalCredits += subject.credits
+    }
+
+    result.push({
+      id: sem.baseId + studentId,
+      studentId,
+      semesterName: sem.name,
+      courses,
+      rank: Math.floor(Math.random() * 20) + 1,
+      average: Number((totalScore / totalCredits).toFixed(2)),
+    })
+  }
+  return result
+}
+
+for (let i = 1; i <= 20; i++) {
+  seedSemesters.push(...generateMockSemesters(i))
+}
+
+export const useSemesterStore = defineStore('semesters', () => {
+  const semesters = ref<SemesterRecord[]>([...seedSemesters])
+
+  const getStudentSemesters = (studentId: number) => {
+    return semesters.value.filter((s) => s.studentId === studentId)
+  }
+
+  const generateForStudent = (studentId: number) => {
+    const newSemesters = generateMockSemesters(studentId)
+    semesters.value.push(...newSemesters)
+  }
+
+  const addSemester = (studentId: number) => {
+    const newId = Math.max(...semesters.value.map((s) => s.id), 0) + 1
+    const newSemester: SemesterRecord = {
+      id: newId,
+      studentId,
+      semesterName: '新學期',
+      courses: [],
+      rank: 0,
+      average: 0,
+    }
+    semesters.value.push(newSemester)
+    return newSemester
+  }
+
+  const updateSemester = (id: number, payload: Partial<SemesterRecord>) => {
+    const index = semesters.value.findIndex((s) => s.id === id)
+    if (index === -1) return
+    const current = semesters.value[index]
+    if (!current) return
+
+    if (payload.courses) {
+      const totalScore = payload.courses.reduce((sum, c) => sum + c.score * c.credits, 0)
+      const totalCredits = payload.courses.reduce((sum, c) => sum + c.credits, 0)
+      payload.average = totalCredits > 0 ? Number((totalScore / totalCredits).toFixed(2)) : 0
+    }
+
+    Object.assign(current, payload)
+  }
+
+  const removeSemester = (id: number) => {
+    const index = semesters.value.findIndex((s) => s.id === id)
+    if (index !== -1) {
+      semesters.value.splice(index, 1)
+    }
+  }
+
+  const removeByStudentId = (studentId: number) => {
+    semesters.value = semesters.value.filter((s) => s.studentId !== studentId)
+  }
+
+  return {
+    semesters,
+    getStudentSemesters,
+    generateForStudent,
+    addSemester,
+    updateSemester,
+    removeSemester,
+    removeByStudentId,
+  }
+})