setdb: lwdb-native local-DB switcher + release-aware installer

[sibinc]

What

Adds lwdb setdb — points the local Linways app at a chosen server+db by rendering a single PHP include (active-db.php) from a connection in the lwdb store. Replaces the old standalone setDB PHP script + in-repo dbconfs/*.txt credential files.

setdb command

• Interactive for humans (TTY); --json for agents (strict exit codes).
• --status, --print (dry run), --init (create file + print the include line to paste, flagged "must be LAST").
• Connections/creds sourced from the lwdb store (registry.getConnection) — nothing secret in any app repo.
• Correct PHP escaping via single-quoted literals ($/%/' safe) — fixes the old concat approach.

Config homed in ~/.lwdb/

• ~/.lwdb/setdb.json (targets: output path, includeInto, group, verify) and ~/.lwdb/college-codes.json (code map).
• Both auto-seeded by install/update (never clobbering an edited config); includeInto ships empty (machine-specific).
• active-db.php defaults to ~/.lwdb/dev/active-db.php — app tree stays clean; conf files include it by absolute path.

Installer

• Release-aware update: compares latest GitHub release to the installed desktop .deb, prompts, installs.

Tests

12/12 pass: setdbTarget, setdbConfig, install suites (render/escaping, config discovery + home fallback, seeding no-clobber, semver/deb-asset).

Docs: docs/setdb.md.