chore(repo): initialize Cowork Local Gitea repository

core/java_runtime.py

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+"""Optional Java runtime detection.
+
+``opendataloader-pdf`` (structured PDF→JSON extraction, see chat_agent.py) is a
+Python wrapper around a JAVA CLI tool — the first Java dependency anywhere in
+this app. Same optional-native-binary shape as doc_extract.py::find_soffice:
+env override → PATH → common install directories → ``None`` if not found.
+Callers must degrade gracefully — a missing JVM just means that one capability
+isn't available on this machine, not an error.
+"""
+from __future__ import annotations
+
+import os
+import re
+import shutil
+from pathlib import Path
+
+_EXE = "java.exe" if os.name == "nt" else "java"
+
+# Common JDK/JRE install roots, newest-version subfolder picked first.
+_COMMON_ROOTS = (
+    r"C:\Program Files\Java",
+    r"C:\Program Files\Eclipse Adoptium",
+    r"C:\Program Files (x86)\Java",
+    "/Library/Java/JavaVirtualMachines",
+    "/usr/lib/jvm",
+)
+
+
+def _version_key(path: Path) -> tuple:
+    """Natural-sort key so "jdk-17..." ranks above "jdk-8..." — a plain string
+    sort ranks '8' > '1' and would pick the OLDER JDK when major-version digit
+    counts differ (e.g. Eclipse Adoptium installs several majors side by side
+    under one root)."""
+    return tuple(int(n) for n in re.findall(r"\d+", path.name))
+
+
+def find_java() -> str | None:
+    """Locate a Java launcher (``JAVA_HOME`` → PATH → common install dirs)."""
+    env = os.environ.get("JAVA_HOME")
+    if env:
+        candidate = Path(env) / "bin" / _EXE
+        if candidate.exists():
+            return str(candidate)
+    found = shutil.which("java")
+    if found:
+        return found
+    for base in _COMMON_ROOTS:
+        base_path = Path(base)
+        if not base_path.is_dir():
+            continue
+        try:
+            subdirs = sorted(base_path.iterdir(), key=_version_key, reverse=True)
+        except OSError:
+            continue  # unreadable dir (permissions/AV) — not fatal, just try the next root
+        for sub in subdirs:
+            candidate = sub / "bin" / _EXE
+            if candidate.exists():
+                return str(candidate)
+            # macOS JDK bundles nest an extra Contents/Home.
+            mac_candidate = sub / "Contents" / "Home" / "bin" / _EXE
+            if mac_candidate.exists():
+                return str(mac_candidate)
+    return None