feat: bundle Free-Exercise-DB + name matcher (step 1)

Adds the static exercise reference data (~870 entries, public
domain, source: github.com/yuhonas/free-exercise-db) plus a
conservative name matcher. New endpoint:

  GET /api/exercises/lookup?name=<name>
    → {"match": {"name", "primary_muscles", "secondary_muscles",
                 "equipment", "category", "level", ...}}
    → {"match": null}  when nothing plausibly matches.

Matcher tiers (priority order):
  1. exact (case-insensitive)
  2. compressed exact ("Pull-ups" → "Pullups")
  3. compressed substring, with a guard: single-token generics
     like "Bench"/"Squat" return null instead of misleading the
     user — the planned alias table will handle these properly.
  4. token-overlap with ≥50% coverage of the user's tokens.

UI integration ("Trains: chest · shoulders") comes in step 2.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server.py

@@ -18,6 +18,7 @@ from urllib.parse import parse_qs
 from aiohttp import web
 
 from db import init_db, save_workout, get_workouts, get_workout_count, get_stats_sql, delete_workout, update_workout, export_workouts, get_user_workout_number, get_all_exercise_names, log_event, get_settings, update_settings, get_last_exercise
+import exercise_db
 from parser import parse_workout, format_workout
 
 logging.basicConfig(
@@ -293,6 +294,15 @@ async def api_get_last_exercise(request: web.Request):
     return web.json_response({"last": last})
 
 
+@require_auth
+async def api_lookup_exercise(request: web.Request):
+    """Look up an exercise in the static Free-Exercise-DB reference data."""
+    name = request.query.get("name", "").strip()
+    if not name:
+        return web.json_response({"error": "Missing name"}, status=400)
+    return web.json_response({"match": exercise_db.lookup(name)})
+
+
 @require_auth
 async def api_get_stats(request: web.Request):
     """Return summary stats for the user."""
@@ -377,6 +387,7 @@ def create_app() -> web.Application:
     app.router.add_delete("/api/workouts/{workout_id}", api_delete_workout)
     app.router.add_get("/api/exercises", api_get_exercise_names)
     app.router.add_get("/api/exercises/last", api_get_last_exercise)
+    app.router.add_get("/api/exercises/lookup", api_lookup_exercise)
     app.router.add_get("/api/stats", api_get_stats)
     app.router.add_get("/api/export/json", api_export_json)
     app.router.add_get("/api/export/csv", api_export_csv)