ocr.recoverNumericZerosFromCheckboxes: add row-label + positional fallback table finders

Original activity could only find its target table by exact title-text
match on cell r0c0. In production, Azure DI often garbles the section
heading on otherwise-clean form scans, dropping the activity to a no-op
even when the underlying table and its checkbox-misread cells are clearly
present.

Adds two opt-in fallbacks tried in order when the title anchor misses,
gated by a new fallbackTableFinder block on each table config:

  fallbackTableFinder.labelAnchor (Group A):
    Scan tables of configured shape (rowCount and columnCount ranges)
    for one whose col-0 cells contain >= minLabelMatches of the
    configured row-label texts. Column mapping reuses the existing
    header-text matcher. Recovers samples where Azure dropped the
    title but kept the row labels intact.

  fallbackTableFinder.positionalAnchor (Group B):
    For each candidate by shape, locate each expected row label as a
    loose-substring match on the page paragraphs. Pair each match
    with the candidate's row whose midY is closest. Tally
    `offset = label_index - row_index` votes; require
      top_votes >= minVotes AND top_votes >= dominanceRatio * second_votes
    before committing. Apply the dominant offset uniformly to map
    rows. Column mapping sorts the candidate's columns by midX and
    assigns left-to-right to the config's prefixes; if there's one
    extra column, drop the column whose cells are predominantly
    pure currency prefix.

Per-cell eligibility (no digits/letters + selection mark overlap +
field currently empty) is unchanged. Strategies are recorded per
config in `metadata.tableFinderStrategy` and flips are bucketed in
`metadata.appliedByStrategy` for downstream auditing.

Without the fallbackTableFinder block, behavior is identical to the
original (title-only) implementation. The SDPR-baked workflow JSON
is updated to enable both fallbacks with reasonable defaults:
shape 18-21 rows × 2-3 cols, minLabelMatches 12, minVotes 3,
dominanceRatio 2.0.

Validated on prod benchmark dfaddb26-… (99 SDPR samples, 213 originally-
missing zeros): title 60 + label-anchor 33 + positional-anchor 18 = 111
flips total. Remaining 102 cases are out of "checkbox-as-zero" scope.
Mirrored in the standalone counterpart at
`scripts/benchmark analysis/recover-numeric-zeros.py` (separate branch).

4 new unit tests cover: Group-A title-miss + label-anchor fallback,
Group-B successful offset-vote mapping (36 flips on a 19×2 with full
label paragraphs), Group-B safe-skip when offset votes are sparse,
Group-B 19×3 candidate where the pure-currency column is dropped to
match the prefix count.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: strukalex

apps/backend-services/src/hitl/tool-manifest.service.ts

@@ -164,13 +164,13 @@ const TOOL_MANIFEST: ToolManifestEntry[] = [
     toolId: "ocr.recoverNumericZerosFromCheckboxes",
     label: "Recover Numeric Zeros from Checkboxes",
     description:
-      "Recover numeric values (typically 0) for custom-model fields that Azure DI misread as selection marks. Per-table config in node parameters: locate the table by header text, map prefix→column and suffix→row, recover only cells with selection-mark markers (no digits/letters) that overlap a page-level selectionMark. Never overwrites populated fields.",
+      "Recover numeric values (typically 0) for custom-model fields that Azure DI misread as selection marks. Per-table config in node parameters: locate the table (title anchor → row-label anchor → positional anchor with offset vote), map prefix→column and suffix→row, recover only cells with selection-mark markers (no digits/letters) that overlap a page-level selectionMark. Never overwrites populated fields. Fallback finders (labelAnchor, positionalAnchor) are opt-in via the fallbackTableFinder block.",
     parameters: [
       {
         name: "tables",
         type: "object",
         description:
-          "Array of { find, columns, rows, recoveryValue?, cellEligibility? }. See temporal correction-tool-registry for the full shape.",
+          "Array of { find, columns, rows, recoveryValue?, cellEligibility?, fallbackTableFinder? }. See temporal correction-tool-registry for the full shape.",
         required: false,
       },
     ],