Implement artifact-level render command with Markdown output and update docs

docs/operations.md

@@ -7,6 +7,7 @@ This document covers runtime operation of the implemented CLI commands:
 - `merge`
 - `trim`
 - `normalize`
+- `render`
 
 ## Runtime model
 
@@ -29,6 +30,7 @@ Command-specific expectations:
 - `merge`: requires at least one `--input-file`; optional `--speakers` and `--autocorrect` paths must exist when provided.
 - `trim`: input must be an existing valid seriatim artifact JSON file.
 - `normalize`: input must be a JSON object with `segments` or a top-level segment array.
+- `render`: input must be an existing valid seriatim artifact JSON file.
 
 ## Normal workflow
 
@@ -80,11 +82,28 @@ go run ./cmd/seriatim normalize \
   --report-file normalize-report.json
 ```
 
+### Render
+
+1. Provide existing seriatim artifact with `--input-file`.
+2. Provide `--output-file`.
+3. Provide `--format markdown`.
+4. Optionally provide `--title`, `--include-timestamps`, `--include-segment-ids`, and `--include-metadata`.
+
+Example:
+
+```sh
+go run ./cmd/seriatim render \
+  --input-file normalized.json \
+  --output-file transcript.md \
+  --format markdown
+```
+
 ## Output and report artifacts
 
-Primary output:
+Primary outputs:
 
-- `--output-file` writes JSON transcript artifact in selected schema.
+- `merge`, `trim`, `normalize`: `--output-file` writes JSON transcript artifact in the selected schema.
+- `render`: `--output-file` writes presentation Markdown.
 
 Optional report output:
 
@@ -92,6 +111,7 @@ Optional report output:
 - `merge` report metadata records reader/modules and event sequence.
 - `trim` report includes a `trim-audit` event with mode/selector/counts and old-to-new ID mapping.
 - `normalize` report includes a `normalize-audit` event with input shape, repair stats, and output selection details.
+- `render` has no report output in the current implementation.
 
 ## Failure and retry behavior
 
@@ -106,9 +126,10 @@ Retry guidance:
 2. Re-run the same command.
 3. If a prior run created a partial or unwanted output/report file, remove it and rerun.
 
-Operational note:
+Operational notes:
 
-- With identical inputs/config/version, merge behavior is deterministic and input files are sorted before processing.
+- With identical inputs/config/version, `merge` behavior is deterministic and input files are sorted before processing.
+- With identical input artifact and render flags, `render` output is deterministic.
 
 ## Cleanup
 
@@ -124,6 +145,7 @@ Transcript artifacts and reports are local files and may contain sensitive conve
 - Store outputs in controlled directories with appropriate OS permissions.
 - Share report files carefully; they include file paths and processing diagnostics.
 - Normalize report events intentionally avoid embedding transcript text, but output artifacts contain transcript content.
+- Rendered Markdown is human-readable transcript content and should be handled as sensitive output when applicable.
 
 ## Related docs