fix: kickoff_post uses append_and_apply per-event (no full replay)

The route appended 6 events with append_event() and then called
project(conn) to apply them all at once. project() replays the
*entire* event log, but _apply_chat_created in chat/state/world.py
uses raw INSERT (not INSERT OR REPLACE), so the moment a second bot
got kicked off, projecting hit the existing chat_<bot_id> row from
the first kickoff and 500'd with sqlite3.IntegrityError: UNIQUE
constraint failed: chats.id.

Switch to append_and_apply (the live-path pattern in
chat/eventlog/log.py) which appends and applies only the new event
through its registered handler — leaving prior state untouched.
project() / append_event() imports are now unused in this file
and removed.

Suite: 470 passed in 11.8s. Verified manually: a second bot's
kickoff now redirects to /chats/chat_<bot_id> instead of 500ing.

chat/web/kickoff.py

@@ -17,8 +17,7 @@ from fastapi import APIRouter, Depends, Form, HTTPException, Request
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.templating import Jinja2Templates
 
-from chat.eventlog.log import append_event
-from chat.eventlog.projector import project
+from chat.eventlog.log import append_and_apply
 from chat.llm.client import LLMClient
 from chat.services.kickoff import parse_kickoff
 from chat.state.entities import get_bot, get_you
@@ -263,8 +262,14 @@ async def kickoff_post(
     ).fetchone()
     container_id = next_container_row[0]
 
+    # Use ``append_and_apply`` per event (live-path pattern) rather than
+    # appending all-then-project. ``project()`` replays the *entire*
+    # event log; non-idempotent handlers like ``_apply_chat_created``
+    # (raw INSERT into chats) then 500 with UNIQUE constraint failures
+    # for any chats that already exist from prior kickoffs.
+
     # 1. chat_created
-    append_event(
+    append_and_apply(
         conn,
         kind="chat_created",
         payload={
@@ -277,7 +282,7 @@ async def kickoff_post(
     )
 
     # 2. container_created
-    append_event(
+    append_and_apply(
         conn,
         kind="container_created",
         payload={
@@ -293,7 +298,7 @@ async def kickoff_post(
     bot_interruptible = bool(bot_activity_action_interruptible)
 
     # 3. activity_change for "you"
-    append_event(
+    append_and_apply(
         conn,
         kind="activity_change",
         payload={
@@ -314,7 +319,7 @@ async def kickoff_post(
     )
 
     # 4. activity_change for bot
-    append_event(
+    append_and_apply(
         conn,
         kind="activity_change",
         payload={
@@ -335,7 +340,7 @@ async def kickoff_post(
     )
 
     # 5. scene_opened
-    append_event(
+    append_and_apply(
         conn,
         kind="scene_opened",
         payload={
@@ -352,7 +357,7 @@ async def kickoff_post(
     facts = _parse_facts(edge_seed_knowledge_facts)
     if edge_seed_summary.strip():
         facts.insert(0, f"[summary] {edge_seed_summary.strip()}")
-    append_event(
+    append_and_apply(
         conn,
         kind="edge_update",
         payload={
@@ -363,9 +368,4 @@ async def kickoff_post(
         },
     )
 
-    # Project all events at once. ``bot_authored`` (already in log from prior
-    # POST) is idempotent (INSERT OR REPLACE); the new events project cleanly
-    # because they're being applied for the first time.
-    project(conn)
-
     return RedirectResponse(url=f"/chats/{chat_id}", status_code=303)