fix(webui): authority-aware ownership + redacted contamination text (#641)

Addresses the two blockers from the PR #898 review at a81db754.

B1 - degraded ownership inventory was rendered as affirmative absence.
_build_session_rows read the sessions/leases/locks sections without
consulting their status, so a session row emitted lease_ids=() and
worktree_paths=() whether the session genuinely held nothing or the
lease store simply could not be read. The renderer printed both as
"none" and "unbound", contradicting the ownership_authority_complete
invariant documented on InventorySnapshot.

SessionRow now carries lease_authority and worktree_authority. A
worktree binding is correlated through lease work numbers, so it is
unproven when either the leases or the locks section fails to read --
this covers the narrow variant where locks hold real worktree paths but
a degraded leases section leaves work_numbers empty. The renderer emits
"unknown (inventory <status>)" with an authority-unproven badge instead
of none/unbound, the card names the unreadable sections, and an empty
session list from an unreadable sessions section no longer reads as
"no sessions recorded". snapshot_to_dict exports
ownership_authority_complete, ownership_section_status, and per-row
lease_authority / worktree_authority so /api/sessions consumers can
distinguish the two cases.

B2 - contamination payload strings bypassed redaction.
_inspect_contamination copied command_summary, session_id, role and
reason_class out of the marker payload with only str(), while every
inventory-sourced field on the same page arrives through
webui.inventory.scrub(). The write-time redactor
stable_branch_push_guard.redact_command is a narrow denylist that leaves
absolute $HOME paths, -H 'X-Api-Key: <value>', --password <value>, and
PRIVATE_KEY=<value> intact, and this is the first web surface to render
command_summary at all.

Adds webui.inventory.scrub_text(), which collapses $HOME and redacts
credential-shaped tokens and URL userinfo anywhere inside a string rather
than only at its start, and routes the marker payload through it. scrub()
and every existing caller are untouched. The command_summary field is
kept: it is the #630 evidence naming which daemon was killed. The module
docstring claiming absolute paths were already collapsed is corrected.

Also: removes the locks_by_session_hint dead loop and its discard (N1),
adds the missing trailing newline to webui/runtime_views.py (N4), drops
an unused dataclasses.field import, and documents both honesty rules in
docs/webui-local-dev.md.

Tests: tests/test_webui_sessions_view.py grows from 12 to 26 cases,
covering degraded and unavailable ownership sections in both the HTML and
JSON paths, the locks-readable/leases-degraded variant, a guard against
over-correcting clean inventory into "unknown", the previously untested
expired-lease flag, HTML escaping of hostile values in clean and degraded
renders, and each secret class the write-time denylist misses. The
STATUS_UNAVAILABLE import that was present but unused is now exercised.

Validation, from the issue worktree with venv/bin/python (Python 3.14.5,
pytest 9.1.1):

  pytest tests/test_webui_sessions_view.py tests/test_webui_*.py -q
    -> 512 passed, 376 subtests (was 498 / 372; +14 new tests)
  pytest tests/test_issue_854_semantic_container_exclusion.py -q
    -> 13 passed, 8 subtests
  13-file runtime/health/inventory/restart set
    -> 1 failed, 223 passed; the single failure is
       test_runtime_clarity.py::TestRuntimeClarity::
       test_activate_profile_succeeds_when_enabled, the identical test and
       assertion the reviewer recorded on master at 7af40fb5, so it is
       baseline-equivalent and not introduced here.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

docs/webui-local-dev.md

@@ -307,6 +307,26 @@ reconnect/operator restart docs (`docs/mcp-namespace-eof-recovery.md`,
 document). The page does **not** restart, kill, or take over sessions; manual
 `pkill` of MCP daemons is contamination, not recovery.
 
+Honesty rules specific to this view:
+
+* **Ownership columns never assert absence they cannot prove.** When the
+  `leases` or `locks` section is degraded or unavailable, the Leases and
+  Worktree-binding cells render `unknown (inventory <status>)` with an
+  *authority unproven* badge instead of `none` / `unbound`, and a caveat names
+  the unreadable sections. A worktree binding is correlated through lease work
+  numbers, so it is unproven when *either* section fails to read.
+  `/api/sessions` carries the same facts as `ownership_authority_complete`,
+  `ownership_section_status`, and per-row `lease_authority` /
+  `worktree_authority`, so a JSON consumer can tell "holds none" from "could
+  not be read".
+* **Contamination text is redacted at the display boundary.** Marker payloads
+  (`command_summary`, `reason_class`, `session_id`, `role`) are
+  operator-supplied free text that does not arrive through inventory scrubbing,
+  so they pass through `webui.inventory.scrub_text`, which collapses `$HOME` and
+  redacts credential-shaped tokens and URL userinfo *anywhere* in the string.
+  The write-time redactor is a narrow denylist and is not relied on. The field
+  itself is kept — it is the `#630` evidence naming which daemon was killed.
+
 ## System-health dashboard (#639)
 
 `/system-health` renders the same snapshot the `/api/v1/system/health` API