fix(java): source-code analysis crashes with Path(None) — JDK cache resolution assumes a project dir #256

PROBLEM

Java source-code analysis (CLDK.java(source_code=...), and the deprecated CLDK(language="java").analysis(source_code=...) shim) crashes before the analyzer ever runs:

TypeError: argument should be a str or an os.PathLike object where __fspath__ returns a str, not 'NoneType'

ROOT CAUSE

cldk/analysis/java/codeanalyzer/codeanalyzer.py, _get_codeanalyzer_exec (~line 113):

java_cache = Path(self.analysis_json_path) if self.analysis_json_path else cache_subdir(None, self.project_dir, "java")

In source-code mode BOTH analysis_json_path and project_dir are None, so cache_subdir(None, None, "java") hits Path(None). Broken since 21b3e3b (feat: run codeanalyzer.jar on a fetched Temurin JDK) — i.e. in released v1.4.0 and v1.4.1; predates and is unrelated to the #248 lookup fixes.

WITNESSES

tests/analysis/java/test_java_analysis.py: "Should return a symbol table for source analysis with expected class/method count" and "Should return per-variable initializer text for fields" — the two deterministic failures visible in every release-workflow log and on any healthy dev machine.

FIX CONTRACT

1. When both are None, resolve the JDK cache to a stable user-level dir (e.g. Path.home()/.cldk/java/jdk or platformdirs cache), so source/pipe mode works without a project dir.
2. Both witness tests pass; no behavior change for project-path mode.
3. Branch fix/issue-NNN; one PR.