fix(install): B6 detect.sh + B7 uaml CLI shim + B8 host-wide UAML_CONFIG_DIR

B6: lib/detect.sh ports_in_use pipeline aborted under set -e + pipefail
when no TCP listeners exist (grep -oE returns 1 on empty input). Wrap
the pipeline in a subshell with || true so empty result yields empty
string and exit 0.

B7: install does not put uaml CLI on PATH. Drop /usr/local/bin/uaml
shim that adds /opt/uaml-package to PYTHONPATH and execs python3 -m
uaml.cli.main, so users get \`uaml\` after install without depending on
pip site-packages bin/.

B8: \`uaml license activate KEY\` looks up installations.db under
\$HOME/.uaml of the invoking user (root → /root/.uaml/) but trial
record was written to /home/uaml/.uaml/. Drop /etc/uaml/uaml.env with
UAML_CONFIG_DIR=/home/uaml/.uaml + UAML_LICENSE_FILE=/etc/uaml/license.json,
sourced by the new uaml shim.

Verified locally:
 - B6: empty pipe input now exits 0 (was exit 1 under set -euo pipefail).
 - B9 (separate uaml commit): legacy v6 DB gains raw_content_hash via
   legacy_adds + migration v7.

Refs: AGGREGATE-REPORT-2026-04-30 + UAML-E2E-RESULT-2026-04-30T2230.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
