feat(core): P0 radical evolution — kill blank_start, complete ContextGate matrix, fix HD Map back transitions

P0-2: Kill blank_start: true in config — the nuclear option that wipes ALL learned
knowledge on every run. Replaced with memory_hygiene() selective amnesia that
prunes low-confidence entries while preserving high-confidence learned patterns.

P0-3: Purge all root-level garbage scripts (scratch.py, test_run.py, profile_dump.xml,
resp_dump.json, pytest_output.log, test_output.log, coverage.xml, coverage_e2e.json).
Updated .gitignore to prevent reaccumulation.

P2-2: Replace piecemeal BANNED_SCREENS/REQUIRED_MARKERS with complete Action
Compatibility Matrix (VALID_SCREENS whitelist). Every interaction intent now has
an explicit set of valid screens. Covers like, comment, follow, unfollow, save,
repost across all 14 screen types.

P2-3: Remove non-deterministic 'press back' transitions from HD Map topology for
OTHER_PROFILE, POST_DETAIL, and SEARCH_RESULTS. Add tab transitions to POST_DETAIL.

P2-4: Replace ScreenMemoryDB nuclear 200-entry wipe with LRU eviction.
store_screen() now accepts confidence parameter.

TDD: 22 new tests (all GREEN), 240 unit/tdd/integration passed, 0 regressions.
E2E: 288 passed (+2 fixed), 6 pre-existing LIE DETECTED failures.

.gitignore

@@ -47,6 +47,7 @@ traceback.log
 htmlcov/
 .coverage
 coverage.xml
+coverage_e2e.json
 .hypothesis/
 
 # Local diagnostic traces