Rewrite Python comments in Google developer documentation style (#12)

* Rewrite comments in Google developer documentation style

Rewrite the comments and docstrings across the backend core modules so they
read plainly. The previous prose was accurate but dense and figurative, which
made it slow to skim.

Applies the Google developer documentation style guide: short sentences, active
voice, present tense, American spelling, and no metaphors, idioms, or
rhetorical asides. Replaces em-dash chains with separate sentences.

backend/tools/shots_fixture.py

@@ -5,12 +5,13 @@ with one stat, because a map only cares about the shape. A screenshot cares
 about everything else: the world-state rail wants a scenario with bands, flags,
 milestones and a named cast, and the story wants prose somebody would read.
 
-So this drives the seeded **Bandit Camp** demo — the same scenario the older
-images were shot on, so the set stays one product — through eight turns of
-written prose and written deltas, and forks three discarded takes onto branches
-of their own — one of them off a branch, so the map has to nest. It leaves the reader on the first telling, on a
-turn that has a second take, so one screen shows the world state, the take
-pager and the branch rail at once.
+So this script drives the seeded Bandit Camp demo through eight turns of written
+prose and written deltas. That is the same scenario the older images were shot
+on, which keeps the set consistent. It then forks three discarded attempts onto
+branches of their own, one of them off a branch, so the map has to nest. It
+leaves the reader on the first telling, on a turn that has a second attempt, so
+one screen shows the world state, the attempt pager, and the branch rail at
+once.
 
     cd backend
     .venv/Scripts/python.exe -m tools.shots_fixture /tmp/shots.db
@@ -123,9 +124,9 @@ TURNS = [
     ),
 ]
 
-# The takes the story did not keep. Each is retried at the turn of the same
-# index below, and then forked onto a branch of its own — a discarded take is
-# the only thing a fork can be made of.
+# The attempts the story did not keep. Each one is retried at the turn with the
+# same index below, and then forked onto a branch of its own. A discarded attempt
+# is the only thing a fork can be made from.
 RETAKES = {
     3: (
         "He passes close enough that you can smell the tar on his coat, and the "
@@ -145,8 +146,11 @@ RETAKES = {
 
 
 class ScriptedProvider:
-    """Serves whatever the driver loaded, so a retry can differ from the take
-    it replaces — which is the whole thing being photographed."""
+    """Serves whatever the driver loaded, so a retry can differ from the attempt
+    it replaces.
+
+    That difference is what the screenshots show.
+    """
 
     next_reply = ("", {})
 
@@ -165,9 +169,9 @@ auth.resolve_provider_config = lambda s: auth.ProviderConfig(
 limits.rate_limit = lambda *a, **k: None
 limits.check_row_cap = lambda *a, **k: None
 
-# `bootstrap()` runs at import and seeds the public demo scenarios, so the
-# Bandit Camp is already here — the point of shooting on it is that it is the
-# scenario a visitor actually meets.
+# `bootstrap()` runs at import and seeds the public demo scenarios, so the Bandit
+# Camp already exists. Shooting on it matters because it is the scenario a
+# visitor meets.
 client = TestClient(app)
 
 db = SessionLocal()
@@ -206,9 +210,11 @@ def retake(i):
 
 
 def retry_last():
-    """Retry whatever is at the tip, with whatever reply is loaded, and hand
-    back the take the story just walked away from — the only thing a fork can
-    be made of."""
+    """Retries whatever is at the tip with whatever reply is loaded.
+
+    Returns the attempt the story just left, which is the only thing a fork can
+    be made from.
+    """
     before = live_ai_ids()
     r = client.post(f"{base}/retry")
     assert r.status_code == 200, r.text
@@ -264,9 +270,9 @@ name([b for b in branches() if b["is_head"]][0]["id"], "Loud, and early")
 
 # ---- and a line that left that one again, so the map has to nest ----
 #
-# Forking the take at the tip only switches to it — the attempts there are
-# still leaves nobody has built on. So the story is moved one turn past it
-# first, and only then is the take it walked away from worth a branch.
+# Forking the attempt at the tip only switches to it, because the attempts there
+# are still leaves that nothing was built on. The story is therefore moved one
+# turn past it first, and only then does the attempt it left deserve a branch.
 ScriptedProvider.next_reply = (
     "Nobody comes. The horn was the wrong horn, or the camp has been empty of "
     "anyone who cares since before you got here.", {"npc.gwen.trust": -4})
@@ -298,8 +304,8 @@ r = client.post(f"{base}/actions", json={"type": "do", "text": "Say nothing and
 assert r.status_code == 200, r.text
 name([b for b in branches() if b["is_head"]][0]["id"], "Said nothing")
 
-# Leave the reader on the first telling, standing on the turn that has two
-# takes — the one screen that shows the rail, the pager and the branches.
+# Leave the reader on the first telling, on the turn that has two attempts. That
+# is the one screen showing the rail, the pager, and the branches.
 client.post(f"{base}/branches/{root}/switch")
 
 with engine.begin() as conn: