Add Language Hints to Untagged Code Fences

SQL block recovered from a query

The block opens with SELECT (case-insensitive), so it is tagged sql on the sixth pattern.

Input:
```
SELECT id, email FROM users WHERE active = 1;
```

Output:
```sql
SELECT id, email FROM users WHERE active = 1;
```

HTML block from a leading tag

A <div start matches the HTML pattern. The match is case-insensitive, so <DIV works too.

Input:
```
<div class="note">Read me first</div>
```

Output:
```html
<div class="note">Read me first</div>
```

Bare config block left untouched

A TOML/INI-style block matches nothing in the chain, so the cleanup pass leaves it exactly as found — no false json or text tag.

Input:
```
[server]
port = 8080
```

Output:
```
[server]
port = 8080
```

Mixed doc: only bare fences change

In a doc with one tagged and one bare fence, only the bare one is modified. The tagged block is byte-identical in the output.

Input:
```json
{ "ok": true }
```

```
def run():
    return True
```

Output:
```json
{ "ok": true }
```

```python
def run():
    return True
```

Re-run is a no-op

Running the cleaned doc through the tagger again changes nothing, because every fence now carries a hint.

Input (already cleaned):
```python
import os
```

Output:
```python
import os
```

If the first line does not hit any of the nine patterns — common for YAML, TOML, Bash, CSS, plain logs — the fence is returned bare. This is deliberate: the cleanup never introduces a wrong tag.

The pass never edits an existing hint. If a contributor tagged a block ``` text and you want bash ```, the tagger leaves it as-is; change it by hand.

Older docs sometimes use ~~~ fences. These are skipped entirely. Convert them to backticks first if you want them tagged in the same cleanup.

Four-space-indented blocks are not fenced, so they are ignored. Wrap them in backtick fences before running if they should be tagged.

Detection reads the top of the block. A block that opens with a comment or blank line usually misses every keyword pattern and stays bare. Reorder so a signature line is first.

JavaScript is checked before Go and both list const /var . A Go block starting with const ( becomes javascript. Lead with package or func for a correct go tag, or fix it manually.

A block whose first non-space character is { or [ is tagged json. Watch for non-JSON content (e.g. a Rust block opening with a brace) being labelled json.

Free tier accepts up to 500,000 characters and 1 MB per file. A doc beyond that is rejected before the pass runs; split it with md-splitter or use a higher tier (Pro: 5,000,000 characters / 10 MB).

This tool takes a single document per run. For a folder-wide cleanup, run each file in turn, or combine them with md-merger first — there is no batch mode for this tool.