feat: drawer edits for edge_trust / edge_summary / memory_pov_summary / knowledge_facts (T72.1)

Adds the four POST routes whose state-layer support was already
dispatched by the manual_edit projector (edge_trust, edge_summary,
memory_pov_summary) plus a new edge_knowledge_fact dispatch branch for
add/remove fact list manipulation. Drawer template gains editable
textareas, sliders, and add/remove fact controls. Remove semantics on
knowledge_fact match by string (not index) so concurrent edge_update
events appending facts between drawer renders don't desync the form.

chat/state/manual_edit.py

@@ -6,7 +6,7 @@ be reversed by emitting an inverse ``manual_edit`` later. This module
 applies the new value to the appropriate target table; the snapshot of
 ``prior_value`` is taken by the route handler before this fires.
 
-Phase 1 covers four target kinds:
+Phase 1 covers five target kinds:
 - ``edge_affinity`` and ``edge_trust`` — slider edits on a specific edge,
   clamped to 0..100.
 - ``memory_significance`` — dropdown edit, clamped to 0..3.
@@ -17,8 +17,12 @@ Phase 1 covers four target kinds:
   field. Driven by T27 from the classifier's ``relationship_summary``
   output combined with the prior summary.
 
-Other §6.4 editable fields (activity verb / attention / posture,
-knowledge_facts list manipulation) are deferred to Phase 1.5.
+T72.1 (Phase 2.5) adds one list-shaped edit:
+- ``edge_knowledge_fact`` — add/remove a single fact on an edge's
+  ``knowledge_json`` list. Payload carries an ``action`` of ``"add"`` or
+  ``"remove"`` and a ``fact`` string; remove matches the first occurrence
+  by string equality so the route handler doesn't have to track fact
+  indices across re-renders.
 
 Pin toggles intentionally use the existing ``memory_pin_changed`` event
 (registered in :mod:`chat.state.memory`) rather than ``manual_edit`` so
@@ -27,6 +31,7 @@ the projection writes both ``pinned`` and ``auto_pinned`` atomically.
 
 from __future__ import annotations
 
+import json
 from sqlite3 import Connection
 
 from chat.eventlog.log import Event
@@ -87,5 +92,33 @@ def _apply_manual_edit(conn: Connection, e: Event) -> None:
                 target_id["target_id"],
             ),
         )
+    elif kind == "edge_knowledge_fact":
+        # T72.1: add or remove a single fact on an edge's knowledge list.
+        # ``target_id`` is the {"source_id", "target_id"} edge pair;
+        # ``new_value`` carries ``{"action": "add"|"remove", "fact": str}``.
+        # Remove matches by string equality (first occurrence) so callers
+        # don't have to thread a fact_index through re-rendered drawers.
+        action = new_value["action"]
+        fact = str(new_value["fact"])
+        row = conn.execute(
+            "SELECT knowledge_json FROM edges "
+            "WHERE source_id = ? AND target_id = ?",
+            (target_id["source_id"], target_id["target_id"]),
+        ).fetchone()
+        if row is not None:
+            knowledge = json.loads(row[0])
+            if action == "add":
+                knowledge.append(fact)
+            elif action == "remove" and fact in knowledge:
+                knowledge.remove(fact)
+            conn.execute(
+                "UPDATE edges SET knowledge_json = ? "
+                "WHERE source_id = ? AND target_id = ?",
+                (
+                    json.dumps(knowledge),
+                    target_id["source_id"],
+                    target_id["target_id"],
+                ),
+            )
     # Unknown target_kind: silently no-op for v1. Future kinds (activity
-    # fields, knowledge_facts list manipulation) extend the dispatch above.
+    # fields, etc.) extend the dispatch above.