Auto-derive run dir from experiment_name + timestamp

Drop checkpoint.directory from config — config defines what an experiment
is, not where its outputs go. The CLI now computes the run directory from
run.experiment_name plus a timestamp, defaulting to runs/tmp/ for
throwaway runs and runs/ when --keep is passed.

- Remove CheckpointConfig.directory and DeepCFRConfig.checkpoint_path
- DeepCFRTrainer takes run_dir: Path explicitly
- CLI: add --keep boolean; --resume requires an explicit path (no shortcut)
- Auto path: runs/[tmp/]<YYYY-MM-DD_HHMMSS>_<experiment_name-kebab>/
- Rename 13 configs to kebab-case; strip directory: lines; kebab their
  experiment_name values
- Rewrite AGENTS.md training/run sections; document
  archive/tmp/<flat> layout, --keep, kebab-case scope
- Update tests for new run_dir flow and dropped --resume shortcut

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

configs/deep_cfr/deep-cfr-color-shared-512x3.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_color_shared_512x3
+  experiment_name: lost-cities-deep-cfr-color-shared-512x3
   seed: 42
   max_iterations: 10000
   max_minutes: null
@@ -85,7 +85,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_color_shared_512x3
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-color-shared-attention-512x3.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_color_shared_attention_512x3
+  experiment_name: lost-cities-deep-cfr-color-shared-attention-512x3
   seed: 42
   max_iterations: 10000
   max_minutes: null
@@ -85,7 +85,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_color_shared_attention_512x3
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-color-shared-attention-exp-1000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_color_shared_attention_1000iter
+  experiment_name: lost-cities-deep-cfr-color-shared-attention-1000iter
   seed: 42
   max_iterations: 1000
   max_minutes: null
@@ -85,7 +85,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_color_shared_attention_exp_1000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-opponent-average-strategy-512x3-1000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_opponent_average_strategy_512x3_1000iter
+  experiment_name: lost-cities-deep-cfr-opponent-average-strategy-512x3-1000iter
   seed: 79
   max_iterations: 1000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_opponent_average_strategy_512x3_1000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-opponent-network-1024x4-1000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_opponent_network_1024x4_1000iter
+  experiment_name: lost-cities-deep-cfr-opponent-network-1024x4-1000iter
   seed: 79
   max_iterations: 1000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_opponent_network_1024x4_1000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-opponent-network-512x3-1000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_opponent_network_512x3_1000iter
+  experiment_name: lost-cities-deep-cfr-opponent-network-512x3-1000iter
   seed: 79
   max_iterations: 1000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_opponent_network_512x3_1000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-pure-selfplay-full-depth-slot-playability-512x3-2x-updates-10000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_pure_selfplay_full_depth_slot_playability_512x3_2x_updates_10000iter
+  experiment_name: lost-cities-deep-cfr-pure-selfplay-full-depth-slot-playability-512x3-2x-updates-10000iter
   seed: 79
   max_iterations: 10000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_pure_selfplay_full_depth_slot_playability_512x3_2x_updates_10000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-anchor-safe-512x3-2x-updates-10000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_anchor_safe_512x3_2x_updates_10000iter
+  experiment_name: lost-cities-deep-cfr-selfplay-anchor-safe-512x3-2x-updates-10000iter
   seed: 79
   max_iterations: 10000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_anchor_safe_512x3_2x_updates_10000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-full-depth-slot-playability-512x3-2x-updates-10000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_full_depth_slot_playability_512x3_2x_updates_10000iter
+  experiment_name: lost-cities-deep-cfr-selfplay-full-depth-slot-playability-512x3-2x-updates-10000iter
   seed: 79
   max_iterations: 10000
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_full_depth_slot_playability_512x3_2x_updates_10000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-full-depth-slot-playability-512x3-lcfr-10000iter.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_full_depth_slot_playability_512x3_lcfr_10000iter
+  experiment_name: lost-cities-deep-cfr-selfplay-full-depth-slot-playability-512x3-lcfr-10000iter
   seed: 79
   max_iterations: 10000
   max_minutes: null
@@ -83,7 +83,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_full_depth_slot_playability_512x3_lcfr_10000iter
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-full-depth-slot-playability-512x3-unbounded.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_full_depth_slot_playability_512x3_unbounded
+  experiment_name: lost-cities-deep-cfr-selfplay-full-depth-slot-playability-512x3-unbounded
   seed: 79
   max_iterations: null
   max_minutes: null
@@ -82,7 +82,6 @@ memory:
   strategy_capacity: 2000000
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_full_depth_slot_playability_512x3_unbounded
   save_latest: true
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-full-depth-slot-playability-unbounded.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_full_depth_slot_playability_unbounded
+  experiment_name: lost-cities-deep-cfr-selfplay-full-depth-slot-playability-unbounded
   seed: 79
   max_iterations: null
   max_minutes: null
@@ -86,6 +86,5 @@ evaluation:
     - noisy_safe
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_full_depth_slot_playability_unbounded
   save_every: 100
   progress_interval_seconds: 20.0

configs/deep_cfr/deep-cfr-selfplay-full-depth-slot-playability.yaml

@@ -1,5 +1,5 @@
 run:
-  experiment_name: lost_cities_deep_cfr_selfplay_full_depth_slot_playability
+  experiment_name: lost-cities-deep-cfr-selfplay-full-depth-slot-playability
   seed: 79
   max_iterations: null
   max_minutes: 240
@@ -86,6 +86,5 @@ evaluation:
     - noisy_safe
 
 checkpoint:
-  directory: runs/deep_cfr/deep_cfr_selfplay_full_depth_slot_playability
   save_every: 10
   progress_interval_seconds: 20.0

configs/deep_cfr/smoke.yaml

@@ -1,4 +1,5 @@
 run:
+  experiment_name: smoke
   max_iterations: 1
   seed: 1
   device: cpu
@@ -25,7 +26,6 @@ memory:
   strategy_capacity: 1000
 
 checkpoint:
-  directory: runs/deep_cfr/smoke
   save_every: 0
   save_latest: false