fix(sessions): keep cwd filters within case-distinct workspaces

[Bryson11111w]

What does this PR do?

Keep directory-scoped session operations inside the selected workspace. With ended sessions in /work/Agent/src and /work/agent/src, filtering by /work/Agent currently selects both: SQLite LIKE folds ASCII case even when its wildcard characters are escaped. prune_sessions() consequently deletes both sessions, and workspace resume, listing and bulk archive use the same predicate.

Use literal instr(...)=1 prefix comparisons with a trailing path separator, matching the case sensitivity of the existing exact-directory comparison. This preserves literal %, _ and backslashes and excludes similarly named sibling directories. Reuse the predicate for legacy Kanban worker retagging, which otherwise misclassifies unrelated CLI sessions and misses backslash-delimited descendants.

Related Issue

Found while reviewing the session persistence code on main at 8df0a03793784205833f9e0db12395aa33ada433; no new issue has been filed. Related prior fix: #78927 escaped SQL wildcards, but LIKE still folds ASCII case. This change addresses that remaining path-boundary failure.

Type of Change

• Bug fix

Changes Made

• hermes_state_sessions.py: use literal, separator-bounded comparisons in the shared cwd predicate.
• hermes_state.py: reuse that predicate when retagging legacy Kanban workers.
• tests/hermes_state/test_cwd_prefix_isolation.py: two behavioral tests, parameterized over slash- and backslash-delimited stored paths. Exercise real SessionDB imports and SQLite databases under isolated HERMES_HOME values.

How to Test

scripts/run_tests.sh \
  tests/hermes_state/test_cwd_prefix_isolation.py \
  tests/hermes_state/test_session_workspace_binding.py \
  tests/hermes_cli/test_kanban_worker_session_source.py \
  tests/hermes_state/test_session_archiving.py \
  -j 1 --file-retries 0 --tb=short

scripts/run_tests.sh tests/hermes_state/test_hermes_state.py \
  -j 1 --file-retries 0 -k cwd_prefix --tb=short

Results on Linux / Python 3.12.13:

• Before the production change, all four new parameterized cases fail on the base commit: directory filtering admits the case-distinct sibling; worker retagging either admits it or misses the backslash descendant.
• After the change, the first command passes 17 tests and the second passes four existing cwd-filter regressions: 21 passed, zero failed, with retries disabled.
• git diff --check passes.

Rebased onto main at 633dda6d7fdcac7e8340471c9f5ed08cdccbd70c and reran both focused commands: 21 passed, zero failed. The affected production paths were unchanged between the original reproduction and this base.

The new tests cover listing/count agreement, workspace lookup, prune preview/count agreement, archive/delete isolation, literal wildcard characters, separator boundaries and one-time worker retagging. Stored Windows-style paths are exercised as data on Linux; native Windows and macOS have not been run. No live provider or full-suite claim.

Checklist

• Read the contributing guide and applicable area instructions.
• Searched existing issues/PRs for cwd_prefix and reviewed the earlier wildcard fix.
• Changes are limited to the cwd-boundary bug and its sibling retag path.
• Added behavioral regression tests demonstrated to fail on base.
• Ran focused checks with scripts/run_tests.sh.
• Full test suite passed (not run).
• Tested on Linux with isolated real SQLite databases.
• No configuration keys, tool schemas or documented import paths changed.