nx_doc_autoheal.nx

nx_doc_autoheal.nx -- the Doctor's autonomous RESOLVE loop. Closes the two halves the team already has (RECALL: the ki- known-issue catalogue; FIX: nx_doc_heal_let) into ONE hands-free pass: given a source that hit the empty-.s symptom AND the diagnostic the runner/compiler emitted, it (1) RECALLs the lesson from the catalogue, (2) ROUTEs to the matching auto-fixer iff the recalled class is one we can fix, (3) APPLIEs the fix, and (4) VERIFIEs the defect is actually gone (static post-condition: no reassigned `let` remains). The real recompile is the caller's next step on the healed bytes -- nesting a full rebuild HERE would trip NX-GATE-NESTED-BUILD (a lesson we recorded), so the safe, honest boundary is decision+transform+postcondition. Honest by construction: no recall -> DAH_UNKNOWN (invents nothing); recalled but not our class / no applicable change -> DAH_NOFIX (does not falsely claim a heal); only a verified-clean rewrite returns DAH_HEALED. license_tier: ORIGINAL