feat(project): 달력을 휴가 모듈식 월간 그리드로 교체

FullCalendar 제거. 휴가 모듈과 동일한 서버 렌더 월간 달력(구글식 bar
레인 배치)로 변경. 업무 start~due 기간을 bar 로 표시, 클릭 시 모달.
?y=&m= 로 월 이동, 프로젝트 색상 반영, 완료 업무는 회색+취소선.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/modules/project/router.py

@@ -14,7 +14,9 @@
 
 from __future__ import annotations
 
+import calendar as _calendar
 import logging
+from datetime import date
 from typing import Any
 
 from fastapi import APIRouter, BackgroundTasks, Body, Depends, HTTPException, Request
@@ -132,6 +134,96 @@ def _build_tree(projects: list[dict[str, Any]]) -> list[dict[str, Any]]:
     return roots
 
 
+# ────────────────────────────────────────────────────────────
+# 월간 달력 레이아웃 (휴가 모듈과 동일한 구글식 bar 레인 배치)
+# ────────────────────────────────────────────────────────────
+def _assign_lanes(bars: list[dict[str, Any]]) -> int:
+    """주(week) 내 bar 들에 겹치지 않는 lane(행)을 그리디 배정. 사용 lane 수 반환."""
+    bars.sort(key=lambda b: (b["start_col"], -b["span"]))
+    lane_end: list[int] = []  # lane 별 마지막 점유 col(포함)
+    for b in bars:
+        placed = False
+        for li, end_col in enumerate(lane_end):
+            if b["start_col"] > end_col:
+                b["lane"] = li
+                lane_end[li] = b["start_col"] + b["span"] - 1
+                placed = True
+                break
+        if not placed:
+            b["lane"] = len(lane_end)
+            lane_end.append(b["start_col"] + b["span"] - 1)
+    return len(lane_end)
+
+
+def _task_span(task: dict[str, Any]) -> tuple[date, date] | None:
+    """업무의 달력 표시 기간(start..due). 둘 중 하나만 있으면 단일일. 없으면 None."""
+    s = task.get("start_date")
+    d = task.get("due_date")
+    try:
+        sd = date.fromisoformat(s[:10]) if s else None
+        dd = date.fromisoformat(d[:10]) if d else None
+    except (ValueError, TypeError):
+        return None
+    if sd and dd:
+        return (sd, dd) if sd <= dd else (dd, sd)
+    if sd:
+        return (sd, sd)
+    if dd:
+        return (dd, dd)
+    return None
+
+
+def _build_task_calendar(
+    tasks: list[dict[str, Any]], year: int, month: int
+) -> list[dict[str, Any]]:
+    """업무 리스트 → 월간 달력 주(week) 데이터(휴가 _build_calendar 와 동일 구조)."""
+    cal = _calendar.Calendar(firstweekday=6)  # 일요일 시작
+    weeks_dates = cal.monthdatescalendar(year, month)
+    today = today_kst()
+
+    spans: list[tuple[date, date, dict[str, Any]]] = []
+    for t in tasks:
+        sp = _task_span(t)
+        if sp:
+            spans.append((sp[0], sp[1], t))
+
+    weeks: list[dict[str, Any]] = []
+    for week in weeks_dates:
+        w_start, w_end = week[0], week[-1]
+        days = [
+            {
+                "date": d.isoformat(),
+                "day": d.day,
+                "in_month": d.month == month,
+                "is_today": d == today,
+                "is_sunday": d.weekday() == 6,
+                "is_saturday": d.weekday() == 5,
+            }
+            for d in week
+        ]
+        bars: list[dict[str, Any]] = []
+        for rs, re_, t in spans:
+            if re_ < w_start or rs > w_end:
+                continue
+            seg_start = max(rs, w_start)
+            seg_end = min(re_, w_end)
+            bars.append(
+                {
+                    "id": t["id"],
+                    "label": t["title"],
+                    "color": t.get("project_color") or "#4573d2",
+                    "completed": bool(t.get("completed_at")),
+                    "start_col": (seg_start - w_start).days,
+                    "span": (seg_end - seg_start).days + 1,
+                    "continues_left": rs < w_start,
+                    "continues_right": re_ > w_end,
+                }
+            )
+        lane_count = _assign_lanes(bars)
+        weeks.append({"days": days, "bars": bars, "lane_count": lane_count})
+    return weeks
+
+
 # ────────────────────────────────────────────────────────────
 # 페이지
 # ────────────────────────────────────────────────────────────
@@ -206,6 +298,19 @@ async def project_page(request: Request, project_id: int) -> HTMLResponse:
     can_manage = _can_manage(request, st, user, project_id)
     subprojects = [p for p in all_projects if p.get("parent_id") == project_id]
 
+    # 달력(휴가식 월간 그리드) — ?y=&m= 로 월 이동, 기본 이번 달
+    today = today_kst()
+    try:
+        year = int(request.query_params.get("y") or today.year)
+        month = int(request.query_params.get("m") or today.month)
+        if not (1 <= month <= 12):
+            year, month = today.year, today.month
+    except (TypeError, ValueError):
+        year, month = today.year, today.month
+    weeks = _build_task_calendar(tasks, year, month)
+    prev_y, prev_m = (year - 1, 12) if month == 1 else (year, month - 1)
+    next_y, next_m = (year + 1, 1) if month == 12 else (year, month + 1)
+
     return render_template(
         request,
         "project/project.html",
@@ -224,7 +329,13 @@ async def project_page(request: Request, project_id: int) -> HTMLResponse:
             "subprojects": subprojects,
             "priority_labels": store.PRIORITY_LABELS,
             "color_palette": list(store.COLOR_PALETTE),
-            "today": today_kst().isoformat(),
+            "today": today.isoformat(),
+            "year": year,
+            "month": month,
+            "prev_y": prev_y, "prev_m": prev_m,
+            "next_y": next_y, "next_m": next_m,
+            "weekdays": ["일", "월", "화", "수", "목", "금", "토"],
+            "weeks": weeks,
         },
     )