docs+fix: restore README.adoc, repoint licence badge → MPL-2.0, SHA-pin trufflehog (#41)

<!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
## What

Three feedback-o-tron corrections (all owner-approved 2026-07-01):

1. **README `.md` → `.adoc`** — commit `fb92b30` had converted
`README.adoc → Markdown` ("renders on Glama/profile"), but that `.md`
rationale is the estate exception for **only** `boj-server` + the
profile repo. Recovered the pristine original `README.adoc` from
`fb92b30^` (791 lines, verbatim) and deleted the mangled `.md` —
reversing the exact wrong conversion.
2. **Licence badge → MPL-2.0** — the badge text was already MPL-2.0 but
its link pointed at `hyperpolymath/palimpsest-license` (a leftover from
before this repo's PMPL→MPL-2.0 migration `bf93f4f`). Repointed to the
MPL-2.0 licence and cleaned the mangled badge image. feedback-o-tron is
not a PMPL carve-out.
3. **SHA-pin trufflehog** — `secret-scanner.yml` used
`trufflesecurity/trufflehog@main`, the sole unpinned action the
`governance / Workflow security linter` flagged. Pinned to
`@f446421baf832d6356c42c1743d99abff52ff334` (v3.95.7, resolved via the
GitHub API). This turns that pre-existing red check green.

## Verification

- Linter's exact grep → **no unpinned actions** (governance check will
pass).
- `asciidoctor --failure-level=WARN README.adoc` → **0 warnings**; no
palimpsest reference remains.
- `README.md` deleted (no duplicate); no V-lang token.

Note: the CodeQL `analyze (javascript-typescript)` red is separate and
pre-existing (unaffected by these changes).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/secret-scanner.yml

@@ -21,6 +21,6 @@ jobs:
         with:
           fetch-depth: 0
       - name: TruffleHog Secret Scan
-        uses: trufflesecurity/trufflehog@main
+        uses: trufflesecurity/trufflehog@f446421baf832d6356c42c1743d99abff52ff334 # v3.95.7
         with:
           extra_args: --only-verified --fail