feat(tools): add firebolt_roam — standalone roam-and-cast for levelling

src/run/cold_plains.py needs a waypoint, the town manager and the bot state
machine. None of that is usable for a clvl 1 character standing in Blood Moor,
which has no waypoint at all.

This starts from wherever the character already is: scan with target_detect ->
cast the configured skill at the nearest target -> roam if nothing is visible.
No waypoints, no town, no state machine.

    python tools/firebolt_roam.py --key f1 --minutes 10

The skill is a plain hotkey, so Fire Bolt now and Fireball at clvl 12 is the
same command. Stop key (default F12) is polled between every cast, and there is
a hard --minutes budget.

Explicitly NOT included: potion, chicken or death handling. Documented in the
module docstring — it will keep casting while dying, so it wants supervision.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/firebolt_roam.py

@@ -0,0 +1,111 @@
+"""
+Roam wherever the character is standing and cast one skill at whatever moves.
+
+Built for levelling a fresh character in an open area (Blood Moor, Cold Plains).
+Unlike src/run/cold_plains.py this does NOT use the waypoint, the town manager
+or the bot state machine — it starts from wherever the character already is, so
+it needs no waypoints and works at clvl 1.
+
+    <botty-env-python> tools/firebolt_roam.py --key f1 --minutes 10
+
+Put Fire Bolt on that key in game. At clvl 12 put Fireball on the same key and
+change nothing else.
+
+Press the stop key (default F12) at any time to stop. Ctrl+C also works.
+
+SAFETY: there is no potion, chicken or death handling here. It will happily keep
+casting while dying. Watch it rather than leaving it unattended.
+"""
+import argparse
+import math
+import os
+import random
+import sys
+import time
+
+ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, os.path.join(ROOT, "src"))
+
+
+def main():
+    ap = argparse.ArgumentParser(add_help=True)
+    ap.add_argument("--key", default="f1", help="hotkey holding the attack skill (default: f1)")
+    ap.add_argument("--button", default="right", choices=["left", "right"],
+                    help="mouse button the skill casts on (default: right)")
+    ap.add_argument("--minutes", type=float, default=10.0, help="stop after this long (default: 10)")
+    ap.add_argument("--radius", type=int, default=600, help="ignore targets further than this (px)")
+    ap.add_argument("--casts", type=int, default=4, help="casts per engagement before rescanning")
+    ap.add_argument("--cast-delay", type=float, default=0.25, help="seconds between casts")
+    ap.add_argument("--stop-key", default="f12", help="press to stop (default: f12)")
+    opts = ap.parse_args()
+
+    import screen
+    from config import Config
+    from input_layer import keyboard, mouse
+    from screen import convert_abs_to_monitor
+    from target_detect import get_visible_targets
+    from utils.misc import wait
+
+    screen.find_and_set_window_position(force=True)
+    if not screen.get_offset_state():
+        print("ERROR: D2R window not found. Is the game running and visible?")
+        return 2
+
+    force_move = Config().char["force_move"]
+    deadline = time.time() + opts.minutes * 60
+    kills_attempted = 0
+    roams = 0
+
+    print(f"roaming: key={opts.key} button={opts.button} radius={opts.radius} "
+          f"for {opts.minutes:g} min — press {opts.stop_key.upper()} to stop")
+
+    def stopping() -> bool:
+        try:
+            return keyboard.is_pressed(opts.stop_key)
+        except Exception:
+            return False
+
+    try:
+        while time.time() < deadline:
+            if stopping():
+                print("\nstop key pressed")
+                break
+
+            targets = get_visible_targets(radius_max=opts.radius)
+            if targets:
+                kills_attempted += 1
+                pos = targets[0].center_monitor
+                keyboard.send(opts.key)
+                wait(0.06, 0.12)
+                for _ in range(opts.casts):
+                    if stopping():
+                        break
+                    x = pos[0] + random.randint(-8, 8)
+                    y = pos[1] + random.randint(-8, 8)
+                    mouse.move(x, y, randomize=5, delay_factor=[0.2, 0.4])
+                    mouse.click(button=opts.button)
+                    wait(opts.cast_delay, opts.cast_delay * 1.4)
+            else:
+                roams += 1
+                # y is halved because D2's projection is isometric — an equal
+                # x/y step travels visibly further vertically than horizontally.
+                angle = random.uniform(0, 2 * math.pi)
+                dist = random.randint(150, 260)
+                pos_abs = (math.cos(angle) * dist, math.sin(angle) * dist * 0.5)
+                mx, my = convert_abs_to_monitor(pos_abs)
+                mouse.move(mx, my, randomize=5, delay_factor=[0.2, 0.4])
+                keyboard.send(force_move)
+                wait(0.9, 1.4)
+
+            left = max(0, deadline - time.time())
+            print(f"\r  engagements={kills_attempted}  roams={roams}  {left:5.0f}s left ",
+                  end="", flush=True)
+    except KeyboardInterrupt:
+        print("\ninterrupted")
+
+    print(f"\ndone: {kills_attempted} engagements, {roams} roam steps")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())