v0.8.0 — P4 K2a: reverse-lookup pipeline + verb ingest + stem bridge

Added

• P4 Wave K2a (H181) — reverse-lookup query pipeline, verb-form ingest,
  and the stem-normalization bridge. Executor: Opus 4.8 (claude-opus-4-8).
  • Reverse-lookup cascade (app/reverse_lookup.py)
    behind GET /api/v1/forms/{form}/analyze: inflections exact hit →
    forms witness → vidyut-cheda segmentation of a sandhied/compound
    string, each stage tagged with a resolved_by provenance field
    (inflections/forms/segmentation/null). Segmentation
    (app/segmenter.py)
    runs vidyut 0.4.0 as a local library over vendored data
    (data/vidyut/, gitignored); no live third-party call at build or query
    (RISKS.md R12), and it degrades to an honest miss (segmentation_available: false) when the data isn't vendored.
  • Verb conjugations ingested — the upstream MWinflect Python-2 syntax
    bug in verbs/pysanskritv2/inputs/clean.py (parenthesized-tuple lambda
    parameter) that blocked verbs/redo.sh in K1 is fixed and prepared as an
    on-its-merits upstream PR. scripts/build_inflections.py
    now loads present-system conjugations (pre/ipf/ipv/opt × active/middle/
    passive) into inflections (+67,140 rows; total 6,916,522) with new
    person/tense/voice columns (NULL for nominals). So Bavati now
    resolves as 3sg present of BU.
  • Stem-normalization bridge (scripts/build_stem_bridge.py
    → stem_bridge table, --stage stem_bridge) maps strong/weak stem-spelling
    variants across inflections (Bagavat) and forms (Bagavant) to one
    canonical lemma key. Narrow, data-gated rule (nt→t / drop-final-n, only
    when the two spellings share a surface form) — 380 mappings; the named exit
    case Bagavant → Bagavat unifies to one lemma.
  • Tests: new tests/test_reverse_lookup.py
    (cascade, verb ingest, bridge, segmentation + graceful degradation); full
    suite 161 passed. Documented in
    data/SOURCES.md
    (incl. the ṇatva caveat and the honest dharmakSetre-resolves-at-stage-1
    deviation from the brief's assumption).