fix(inspector): preserve lossy Node discovery locations (#542)

Keep explicitly selected Node Inspector targets observable when discovery
cannot verify their file location. Resolve literal POSIX discovery paths
without URI decoding, and retain lossy Windows or underscore paths as
unresolved metadata. Validate scriptParsed file URLs independently.

Preserve unknown target identity through runtime reconciliation, regenerate
contracts, and verify real CLI/MCP behavior on Linux and Windows.

Closes #530

Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)

docs/javascript-runtime-observation.md

@@ -27,6 +27,38 @@ array.
 
 For the MCP follow-up call, pass the same literal-loopback endpoint and the selected target ID to `observe_javascript_runtime`. REA rediscovers targets and validates the ID against the live endpoint before observation.
 
+### Discovery file locations
+
+Node's `/json/list` reports a best-effort pathname prefixed with `file://`,
+without URI encoding. On POSIX, REA interprets unambiguous paths literally,
+including `#` and `%` in filenames. Node also replaces backslashes and double
+quotes with underscores. That transformation cannot be reversed reliably:
+an underscore may already be part of the original filename.
+
+Windows paths, ambiguous underscore paths, and local discovery paths that
+cannot be verified remain eligible by their endpoint and exact target ID.
+Their target location preserves the reported value:
+
+```json
+{
+  "kind": "unresolved",
+  "reported_url": "file://C:_tools_entry.js",
+  "reason": "unverifiable-file-location"
+}
+```
+
+This location does not claim that a file exists or authorize reading its
+contents. Listing remains HTTP-only. Observation resolves loaded script
+locations independently from `Debugger.scriptParsed` file URLs, preserving
+the existing checks for local files and encoded separators. Unsupported
+schemes, remote file hosts, and a bare `file://` remain excluded. These Node
+discovery rules do not apply to page targets or other runtime products.
+
+Reconciliation retains an unresolved `target_location` object and reports
+`runtime-location-unresolved` with unknown confidence for that target. It
+does not derive a static match from the reported pathname; verified loaded
+script locations remain available for independent matching.
+
 ## Passive protocol boundary
 
 The provider sends exactly two protocol commands: