fix: keep the inventory outside the version-pinned plugin directory (0.3.3)

[CallMeTechie]

The bug

_fleet-lib.sh derived FM_CONTEXT from its own location:

_fm_lib_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
FM_CONTEXT="$(cd "$_fm_lib_dir/.." && pwd)/context"

Claude Code installs plugins into a version-pinned cache path, so on a real install that resolves to:

~/.claude/plugins/cache/fleet-manager/fleet-manager/0.3.2/context

Every claude plugin update creates a new directory. The updated plugin starts with an empty inventory, and the previous version's server profiles, active-server and inventory.md are stranded where nothing reads them. Both directories are already sitting side by side on a machine that has only ever run 0.3.1 → 0.3.2:

.../cache/fleet-manager/fleet-manager/0.3.1/context/
.../cache/fleet-manager/fleet-manager/0.3.2/context/

Silent data loss on a routine update, and the failure mode is confusing: /list-servers reports an empty fleet with no error.

README.md and .gitignore both claimed this layout "survives claude plugin update". It never did.

The fix

Default is now ${XDG_CONFIG_HOME:-~/.config}/fleet-manager. FM_CONTEXT_DIR still overrides, so all 19 existing test call sites are unaffected.

A guarded one-time migration copies a pre-0.3.3 inventory forward. It fires only when the legacy directory holds real profiles and the new one holds none, so it cannot clobber a live inventory, and it copies rather than moves — the originals stay in the old cache directory until the next update discards it.

Verification

tests/unit/test-context-dir.sh, 11 assertions, all passing. It stages a fake version-pinned tree (.../0.3.2/commands/_fleet-lib.sh) and sources the real library from it:

• override precedence, XDG default, $HOME/.config fallback
• the default never resolves back into the plugin directory — this is the regression guard
• migration copies profiles and active-server, skips *.md.template, keeps originals
• migration refuses a populated target, and is a no-op under FM_CONTEXT_DIR

Rest of the suite unchanged: test-fleet-lib 51/51, test-transfer-lib 14/14, test-health-line 3/3, static checks OK, claude plugin validate passes. test-compose-lib shows its usual 2 failures locally for want of docker/jq; they pass in CI.

Note

The /first-run intake agent declares AskUserQuestion in its frontmatter but was dispatched without it, so it cannot ask its intake questions and aborts at the first prompt. Out of scope here — filing separately.