Adds 12 new primitives across two waves of spec work this session.
meta.* layer (8 primitives) — corpus-snapshot footprint:
total_messages, corpus_span_days, msg_per_day, active_days,
activity_density, first_seen_ts, last_seen_ts, fingerprint_confidence.
Motivated by two actors with identical message counts (53 each) producing
indistinguishable profiles despite radically different presence shapes
(0.3-day burst vs 47-day long tail).
Language-aware characterization primitives (4 primitives):
stylometric.pos_ngram_signature — SimHash over POS bigram frequency vector;
syntactic skeleton fingerprint that survives full vocabulary paraphrase.
lexical.dialect_region — BCP-47 free_string (es-CL, es-AR, es-MX, …);
designed for EYENET integration with INGEOTEC regional-spanish-models.
lexical.evaluative_morphology_density — diminutive/augmentative/pejorative
suffix density; stable per-author trait baked into language acquisition.
lexical.optional_grammar_signature — SimHash over optional-grammar choice
points (compound/simple past, subjunctive, leísmo, relative pronoun);
high-reliability Spain vs LatAm discriminator.
Also fixes stale scratchpad.md references throughout (README.md is now the
authority), bumps behave-text to 0.1.3, and updates CHANGELOG.
