uninstall --purge-data and doctor do not address the derived framework state root (~/.agent-bundle/state) or web-data (follow-up to #637, #628)

[ScriptedAlchemy]

#640 (#637) moves the framework state root of installed artifacts from <plugin root>/state to ~/.agent-bundle/state/<plugin>-<digest> ($XDG_STATE_HOME/agent-bundle/<plugin>-<digest>; AGENT_BUNDLE_STATE_ROOT overrides). #628 did the same for the per-server web data directory (~/.agent-bundle/web-data/<plugin>-<digest>/<server>).

The install surfaces still reason only about the legacy in-artifact location:

• agent-bundle uninstall <host> --purge-data --confirm-purge (src/install/uninstall.ts, the emitted install.mjs --uninstall in src/install/surface.ts) purges <install>/state and host plugin-data, reports purged, and leaves the derived state root and web-data directory in the user's home.
• agent-bundle doctor (src/install/doctor.ts inspectDurableState) inventories <pluginRoot>/state only, so the real SQLite kernel, notice ledger and lineage journal of a current install are invisible.

Wanted:

• Purge resolves the derived state root (userDataStateRoot(installPath, env), honoring AGENT_BUNDLE_STATE_ROOT when the receipt/env declares one) and the web-data directory, lists them in --plan, removes them under --purge-data, and keeps the legacy <install>/state handling for pre-feat(runtime): separate the framework state root from the plugin code root #640 installs.
• Doctor inspects the effective state root (with stateSource) and reports the legacy directory separately as retained pre-feat(runtime): separate the framework state root from the plugin code root #640 state.
• Docs (en/zh cli.mdx, installation.mdx) currently state that uninstall does not remove the derived state root; update them with the new behavior.