…a inferSalesforceValueClass helper

RCA: Provar runtime silently discards Salesforce date/datetime fields whose XML emits valueClass="string" — the failure surfaces only when a later validation rule reads the empty field. The existing buildArgumentValue dispatch in src/mcp/tools/testCaseGenerate.ts fell through to a hard-coded valueClass="string" fallback after handling variable / compound / uiTarget / uiLocator cases, so every literal date or boolean argument flowed out untyped. A prior helper (inferValueClass) introduced in 3c1545c that covered the boolean case alone was refactored away in 2d4240c, regressing literal-true/false handling too. Datetime, integer, and explicit org-describe-driven type hints were never covered.

Fix: Introduce an exported inferSalesforceValueClass(key, val, fieldTypeHint?) helper that returns one of 'date' | 'datetime' | 'boolean' | 'integer' | 'string'. Detection order: explicit fieldTypeHint wins; then ISO-8601 datetime regex /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/; then ISO-8601 date regex /^\d{4}-\d{2}-\d{2}$/; then literal 'true'/'false'; then integer-only string /^-?\d+$/; else string. buildArgumentValue now calls this helper before the (now-removed) string fallback and emits <value class="value" valueClass="<inferred>">…</value>. The fieldTypeHint param is wired into the helper signature but not yet exposed on the MCP tool input schema — that exposure lands in PDX-492 H2b, which sits behind PDX-491 H2a (provar_org_describe). Until then callers omit the hint and detection falls through to the regex layer. Tool description and docs/mcp.md argument-conventions table updated to spell out the auto-detection rules.

Tests: New PDX-493 — inferSalesforceValueClass helper block exercises the helper directly across all six branches (datetime with fractional seconds + zone, plain date, true, false, positive integer, negative integer, plain string), the edge case where a short numeric string like "12" must resolve to integer not date (date regex requires full ISO yyyy-mm-dd), strings that look like dates but miss the ISO format must stay string, and explicit fieldTypeHint wins over format detection in all three directions (string-shape + date hint, date-shape + string hint, integer-shape + boolean hint). A second PDX-493 — valueClass emission in generated XML block round-trips through provar_testcase_generate and asserts the inferred attribute reaches the emitted XML for date, datetime, boolean (true and false), positive integer, negative integer, and plain string. Validation: node_modules/.bin/nyc node_modules/.bin/mocha "test/**/*.test.ts" — 1172 passing / 0 failing; yarn compile clean; yarn lint clean (lint:script-names + lint).

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

… (integer → decimal) + anchor datetime regex

RCA: The H3 plan AC specified `valueClass="integer"` for integer-only strings, but
`docs/PROVAR_TEST_STEP_REFERENCE.md` lines 1338 and 1428 are explicit: numbers in
Provar test steps use `valueClass="decimal"` (covering both `42` and `3.14`). No
`integer` valueClass exists in the canonical reference grammar, so the initial
H3 implementation would have emitted XML that diverges from the Provar runtime
contract for every integer field — silently produced bad XML for any numeric
Salesforce field. Separately, the datetime detection regex
`/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/` was not end-anchored, so trailing
garbage after seconds (e.g. `2026-05-19T10:30:00not-a-zone`) was accepted as a
valid datetime and emitted as `valueClass="datetime"`. The canonical reference
permits optional fractional seconds and timezone — the regex must enforce that
shape explicitly.

Fix: In `inferSalesforceValueClass` (src/mcp/tools/testCaseGenerate.ts):
  - Replace the `'integer'` arm of the return-type union with `'decimal'`. Both
    the parameter and return type now use the canonical-reference set:
    `'date' | 'datetime' | 'boolean' | 'decimal' | 'string'`.
  - Broaden the numeric regex from `/^-?\d+$/` to `/^-?\d+(\.\d+)?$/` so it
    matches integers and decimals; return `'decimal'` for both.
  - Anchor the datetime regex end with explicit optional fractional-seconds and
    timezone groups: `/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|[+-]\d{2}:?\d{2})?$/`.
  - Update doc-comment to spell out the canonical reference (lines 1338/1428).
Update tool description text (line ~155) to say "numeric string → decimal" and
explicitly call out that there is no separate `integer` valueClass. Update
`docs/mcp.md` argument-conventions table row to match (one merged numeric row
covering `42`, `-5`, `3.14`). Tests:
  - Rewrite `integer` assertions in test/unit/mcp/testCaseGenerate.test.ts to
    `decimal` (positive int, negative int, short numeric string).
  - Add positive coverage for decimals (`3.14`, `-12.5`) at both helper and
    XML-emission levels.
  - Add datetime end-anchor coverage (numeric timezone offset accepted; trailing
    garbage rejected as `string`).
Addresses Copilot review feedback on PR #183.