fix(jtk): make config show reflect the shared store

[jurij]

Problem

jtk config show skips the shared ~/.config/atlassian-cli/config.yml that the runtime resolvers actually use. After jtk init writes the shared store, config show renders url/email/default_project as empty - rows and prints the legacy per-tool path (which may not even exist) as Config file:. A fully working configuration looks unconfigured:

KEY | VALUE | SOURCE
url |  | -
email |  | -
...
Config file: ~/Library/Application Support/jira-ticket-cli/config.json   # does not exist

while jtk me succeeds. The blind spot was documented in the command's help text, but as a diagnostic surface it misleads more than it explains — I hit it minutes after a successful jtk init.

Fix

• GetURLWithSource, GetEmailWithSource, GetDefaultProjectWithSource now consult the shared store between env and the legacy file — the same precedence the runtime getters use (auth_method and cloud_id already did this via jtkSectionWithSource).
• The Config file: row names the file actually read: the shared store when it exists on disk, else the legacy path.
• The help-text paragraph documenting the old limitation is replaced by the actual precedence.

After

KEY | VALUE | SOURCE
url | https://example.atlassian.net | shared default
email | user@example.com | shared default
api_token | configured | keyring (api_token)
...
Config file: ~/Library/Application Support/atlassian-cli/config.yml

Tests

Two new tests: shared-store values surface with the shared source label and the path row names the shared file; shared beats legacy per field (url from shared, email falling through to legacy). go test ./tools/jtk/... green, gofmt clean.