fix: narrow bare except Exception to specific types where safe

Replace broad except Exception with specific exception types in 6
sites where the expected failure mode is well-defined:

- normalize.py: OSError for file read, ImportError for optional import
- miner.py: OSError for file read_text
- entity_detector.py: OSError for file read in scan loop
- convo_miner.py: (OSError, ValueError) for normalize which reads
  and parses files
- entity_registry.py: (URLError, OSError, JSONDecodeError, KeyError)
  for Wikipedia lookup fallback

ChromaDB except Exception sites (~30) are left broad for now.
chromadb.errors defines NotFoundError, DuplicateIDError,
InvalidDimensionException etc., but narrowing those sites requires
importing from chromadb.errors and validating across supported
versions (>=0.4.0). MCP server handlers also left broad for
resilience.

mempalace/convo_miner.py

@@ -301,7 +301,7 @@ def mine_convos(
         # Normalize format
         try:
             content = normalize(str(filepath))
-        except Exception:
+        except (OSError, ValueError):
             continue
 
         if not content or len(content.strip()) < MIN_CHUNK_SIZE:

mempalace/entity_detector.py

@@ -660,7 +660,7 @@ def detect_entities(file_paths: list, max_files: int = 10) -> dict:
             all_text.append(content)
             all_lines.extend(content.splitlines())
             files_read += 1
-        except Exception:
+        except OSError:
             continue
 
     combined_text = "\n".join(all_text)

mempalace/entity_registry.py

@@ -256,7 +256,7 @@ def _wikipedia_lookup(word: str) -> dict:
                 "note": "not found in Wikipedia — likely a proper noun or unusual name",
             }
         return {"inferred_type": "unknown", "confidence": 0.0, "wiki_summary": None}
-    except Exception:
+    except (urllib.error.URLError, OSError, json.JSONDecodeError, KeyError):
         return {"inferred_type": "unknown", "confidence": 0.0, "wiki_summary": None}
 
 

mempalace/miner.py

@@ -248,7 +248,7 @@ def process_file(
 
     try:
         content = filepath.read_text(encoding="utf-8", errors="replace")
-    except Exception:
+    except OSError:
         return 0
 
     content = content.strip()

mempalace/normalize.py

@@ -27,7 +27,7 @@ def normalize(filepath: str) -> str:
     try:
         with open(filepath, "r", encoding="utf-8", errors="replace") as f:
             content = f.read()
-    except Exception as e:
+    except OSError as e:
         raise IOError(f"Could not read {filepath}: {e}")
 
     if not content.strip():
@@ -213,7 +213,7 @@ def _messages_to_transcript(messages: list, spellcheck: bool = True) -> str:
             from mempalace.spellcheck import spellcheck_user_text
 
             _fix = spellcheck_user_text
-        except Exception:
+        except ImportError:
             _fix = None
     else:
         _fix = None