feat(job): support templ command

docs/JOB_FILES.md

@@ -25,9 +25,10 @@ means adding a vetted adapter in the RelSpec source.
 | `convert`      | read one or more input schemas, additively merge them, write one output |
 | `merge`        | like `convert` but requires ≥2 inputs and exposes `skip_*` merge options |
 | `scripts-list` | deterministically list SQL scripts across one or more directories   |
+| `templ`        | apply a custom Go text template to one or more input schemas          |
 
 Deferred (documented, not implemented here): `scripts` execution against a live
-database, `split`, `inspect`, `diff`, `templ`, job-to-job output wiring,
+database, `split`, `inspect`, `diff`, job-to-job output wiring,
 log rotation/retention. Live SQL execution already exists as
 `relspec scripts execute`; wiring it into the job runner is a follow-up because
 it needs live database credentials and cannot be covered by offline tests.
@@ -123,6 +124,9 @@ jobs:
     script_dirs:                               # scripts-list (≥1)
       - migrations/core
       - migrations/tenant
+    template: templates/schema.tmpl             # templ (required)
+    mode: table                                 # templ: database/schema/script/table
+    filename_pattern: "{{.Name}}.go"           # templ multi-output modes
     output:                                    # convert / merge (required)
       format: pgsql
       path: build/schema.sql                   # file output, OR:
@@ -141,6 +145,11 @@ jobs:
     logfile: .relspec/log/<job-name>.log       # optional; appended to
 ```
 
+For `templ`, `inputs` use the same file or `pgsql`/`conn_env` source forms as
+schema conversion. `output` is optional (empty means stdout); when present it
+contains only `path` and `overwrite`, because templates do not select a schema
+writer format.
+
 ### Supported input formats
 
 `dbml`, `dctx`, `drawdb`, `graphql`, `json`, `yaml`, `gorm`, `bun`, `drizzle`,