Add elapsed run time, per-account results CSV, and a default config path

Summaries now show elapsed wall-clock time since the run started, and every
summary (interim and final) overwrites a results.csv (Object ID, UPN,
persona/status) next to the audit log, so an operator has a plain export
without parsing NDJSON. ConfigPath also now defaults to
./config/persona-engine.json instead of requiring -ConfigPath every run.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

specs/001-persona-engine/contracts/cli-invoke-persona-engine.md

@@ -7,7 +7,7 @@ The engine entry point. Retrieval, evaluation, reporting, and controlled persist
 ```powershell
 [CmdletBinding(SupportsShouldProcess = $true, ConfirmImpact = 'High')]
 param(
-    [Parameter(Mandatory)][string] $ConfigPath,
+    [Parameter()][string] $ConfigPath = './config/persona-engine.json',
     [Parameter()][guid]   $UserObjectId,
     [Parameter()][string] $OutputPath,
     [Parameter()][guid]   $CorrelationId
@@ -21,7 +21,7 @@ parameters and are **not** declared.
 
 | Parameter | Required | Behaviour |
 | --- | --- | --- |
-| `-ConfigPath` | Yes | Path to the JSON configuration. Validated through all four layers before any connection is made (FR-002). |
+| `-ConfigPath` | No | Path to the JSON configuration. Defaults to `./config/persona-engine.json`, resolved against the current directory, when omitted. Validated through all four layers before any connection is made (FR-002). |
 | `-WhatIf` | No | **The approved no-write control.** Reads, evaluation, comparison, console output, summaries, and audit records all behave identically to enforcement; zero write requests are issued (FR-017, SC-004). |
 | `-UserObjectId` | No | Single-user execution for validation. Skips enumeration; retrieves one user. |
 | `-OutputPath` | No | Overrides the configured audit output path where permitted. |
@@ -56,9 +56,12 @@ Failing any of these yields `Unchanged`, `WouldUpdate`, or `Skipped` — never a
 - **Per user, immediately after evaluation** (FR-018, SC-012): one console line carrying UPN,
   Account Object ID, outcome, matched rule ID, stored value, calculated value, and action.
 - **Every `summaryInterval` users** (FR-019): a table of all business rules with match counts, plus
-  outcome totals and a reconciliation check.
+  outcome totals, elapsed wall-clock time since the run started, and a reconciliation check.
 - **At completion**: a final summary regardless of interval, including when the interval is `0`
   (FR-020).
+- **Every summary, interim and final**: `logging.resultsFileName` (default `results.csv`, written
+  next to the audit log) is overwritten with one row per account processed so far — Account Object
+  ID, UPN, and the assigned persona or outcome status.
 - **Reconciliation** at every summary: `Processed = Matched + Unclassified + EvaluationError`
   (FR-021). A mismatch is logged as an engine defect, at `Error` severity.
 - **Audit records**: see [audit-record.md](audit-record.md).