Add HTTP upload configuration support

docs/config.md

@@ -10,7 +10,7 @@ If `--config` is omitted, `run` uses:
 /usr/local/etc/distributor/config.yml
 ```
 
-Config parsing rejects unknown YAML fields. The executable backends are `local`, `ssh`, and `s3`.
+Config parsing rejects unknown YAML fields. The executable `run` backends are `local`, `ssh`, and `s3`. The schema also accepts `http_upload` as a source-only ingestion backend configuration.
 
 ## Minimal Local Config
 
@@ -31,6 +31,14 @@ This publishes source files only. It uses the default validation and transfer po
 ## Production-Oriented Local Config
 
 ```yaml
+server:
+  http:
+    bind: 127.0.0.1:8080
+    staging_root: /var/spool/distributor
+    max_upload_size: 20MB
+    queue_size: 16
+    max_concurrency: 1
+    retention: 24h
 pipelines:
   - id: reports
     source:
@@ -52,6 +60,38 @@ pipelines:
           on_conflict: fail
 ```
 
+## HTTP Upload Source Configuration
+
+HTTP upload sources are configured as pipeline sources only. They are not valid destination backends.
+
+```yaml
+server:
+  http:
+    bind: 127.0.0.1:8080
+    staging_root: /var/spool/distributor
+    max_upload_size: 20MB
+    queue_size: 16
+    max_concurrency: 1
+    retention: 24h
+pipelines:
+  - id: weather-daily
+    source:
+      backend: http_upload
+      token_env: WEATHER_DAILY_UPLOAD_TOKEN
+      staging_path: /var/spool/distributor/weather-daily
+      max_upload_size: 20MB
+    destinations:
+      - id: archive
+        backend: local
+        path: /srv/reports/archive
+```
+
+`source.token_env` is required and names the environment variable or `secrets.directory` file that provides the bearer token. Literal upload tokens are not supported in YAML.
+
+`source.staging_path` is optional. When omitted, it defaults to `<server.http.staging_root>/<pipeline id>`.
+
+`source.max_upload_size` is optional. When omitted, it defaults to `server.http.max_upload_size`.
+
 ## HTML Publication
 
 To publish generated sidecar HTML from Markdown files:
@@ -143,6 +183,12 @@ Output URLs are built from `links.base_url`, the destination bundle path, and th
 
 Top level:
 
+- `server.http.bind`: optional HTTP bind address; defaults to `127.0.0.1:8080`.
+- `server.http.staging_root`: optional root for default HTTP upload staging paths; defaults to `/var/spool/distributor`.
+- `server.http.max_upload_size`: optional default upload size limit; defaults to `20MB`.
+- `server.http.queue_size`: optional HTTP upload admission queue size; defaults to `16`.
+- `server.http.max_concurrency`: optional HTTP upload worker concurrency; defaults to `1`.
+- `server.http.retention`: optional completed upload retention duration; defaults to `24h`.
 - `secrets.directory`: optional credential secrets directory.
 - `pipelines`: required non-empty list.
 
@@ -170,6 +216,9 @@ Source backend:
 - `force_path_style`: optional for `s3`; defaults to `true`. Set `false` only for services that require virtual-host addressing.
 - `credentials.access_key_id_env`: optional S3 credential environment variable name.
 - `credentials.secret_access_key_env`: optional S3 credential environment variable name.
+- `token_env`: required for `http_upload`; names the token environment variable or secret-file name.
+- `staging_path`: optional for `http_upload`; defaults below `server.http.staging_root` using the pipeline id.
+- `max_upload_size`: optional for `http_upload`; defaults to `server.http.max_upload_size`.
 
 Destination:
 
@@ -187,6 +236,20 @@ Accepted backend names:
 - `local`: executable; requires `path`.
 - `ssh`: executable; requires `host` and `path`.
 - `s3`: executable; requires `endpoint` and `bucket`.
+- `http_upload`: source-only configuration; requires `token_env`.
+
+## Size And Duration Values
+
+Upload size fields use an integer plus one of the supported binary-size suffixes:
+
+- `B`
+- `KB`
+- `MB`
+- `GB`
+
+Suffix multipliers use powers of 1024. Size values must be greater than zero after defaults are applied.
+
+HTTP retention uses Go-style duration strings such as `24h`, `90m`, or `168h`. Retention must be greater than zero after defaults are applied.
 
 ## SSH Backend
 
@@ -266,6 +329,14 @@ Defaults are applied after YAML decoding and before validation:
 - SSH `host_key_policy: accept-new`
 - S3 `region: us-east-1`
 - S3 `force_path_style: true`
+- `server.http.bind: 127.0.0.1:8080`
+- `server.http.staging_root: /var/spool/distributor`
+- `server.http.max_upload_size: 20MB`
+- `server.http.queue_size: 16`
+- `server.http.max_concurrency: 1`
+- `server.http.retention: 24h`
+- `source.staging_path: /var/spool/distributor/<pipeline id>` for `http_upload`
+- `source.max_upload_size: server.http.max_upload_size` for `http_upload`
 - `transform.markdown_to_html.mode: sidecar` when a Markdown-to-HTML transform block is present and mode is omitted
 - `publish.source: true`
 - `publish.html: false`