feat(core): consolidate all state under a single env-aware home directory (#462) (#549)

Previously `core/config.py` defined `DEFAULT_CONFIG_DIR = Path.home() /
".openjarvis"` as a by-value module constant imported into ~45 modules, and 34
modules hardcoded `Path.home() / ".openjarvis"` directly. The installer honored
`OPENJARVIS_HOME` but the Python runtime ignored it, producing a split-brain
layout (some modules honored the override, the core config dir did not). Eval
dataset caches also scattered into `~/.cache/<benchmark>`.

This introduces a single env-aware resolver in `openjarvis/core/paths.py` and
routes every state/config/cache path through it. OpenJarvis now keeps ALL of
its state under ONE root, resolved in priority order:

  1. $OPENJARVIS_HOME
  2. $XDG_DATA_HOME/openjarvis   (single nested dir, when XDG_DATA_HOME is set)
  3. ~/.openjarvis               (default — unchanged, so existing installs are
                                  untouched and no data migration is required)

Implementation:
- New `core/paths.py`: get_config_dir / get_config_path / get_data_dir /
  get_cache_dir, with a source-tree rejection guard (fails loudly per
  REVIEW.md if the root resolves inside the repo).
- `core/config.py`: DEFAULT_CONFIG_DIR / DEFAULT_CONFIG_PATH are now resolved
  via the env-aware resolver at import (real attributes, so existing
  monkeypatch.setattr-based tests keep working). All dataclass field defaults
  that pointed at ~/.openjarvis converted to default_factory so they honor the
  override at instantiation.
- Routed all 34 hardcoders plus several string-literal escapees the original
  audit missed: prompt_loader / description_loader (were OPENJARVIS_HOME-only,
  no XDG), swebench_harness cache, tools/{memory,skill,user_profile}_manage
  defaults, server trace.db fallbacks, doctor_cmd hints.
- spec_search storage/paths now delegates to the unified resolver (gains XDG);
  its ConfigurationError is aliased to the core one.
- Eval dataset caches moved from ~/.cache/<name> to <root>/cache/<name>
  (~/.cache/huggingface left alone — it is HF's own cache).
- Docs + installer comment + `jarvis config path` to show resolved dirs.

Read-only macOS connectors and OS service files (LaunchAgents/systemd) are
intentionally left untouched.

Fixes #462

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/install/install.sh

@@ -210,6 +210,14 @@ if ! command -v python3 >/dev/null 2>&1; then
 fi
 
 # ---- env ----
+# OpenJarvis keeps ALL of its state (install tree + runtime data, configs,
+# databases, caches, logs) under a single root so it never clutters $HOME
+# beyond one directory. Relocate it by exporting OPENJARVIS_HOME before
+# running the installer, e.g.:
+#     OPENJARVIS_HOME=~/apps/openjarvis curl ... | bash
+# The Python runtime honors the same override (and, when OPENJARVIS_HOME is
+# unset, $XDG_DATA_HOME/openjarvis if XDG_DATA_HOME is set). With nothing set
+# the root is ~/.openjarvis, so existing installs are untouched.
 OPENJARVIS_HOME="${OPENJARVIS_HOME:-$HOME/.openjarvis}"
 OPENJARVIS_REPO_URL="${OPENJARVIS_REPO_URL:-https://github.com/open-jarvis/OpenJarvis.git}"
 SRC_DIR="$OPENJARVIS_HOME/src"