chore(license): remove stray root Palimpsest licence file (#200)

Owner ruling 2026-09-02: MPL-2.0 for code, CC-BY-SA-4.0 for docs; estate
PMPL sweep Tier 1 (stray siblings); verified in
license-body-verification/VERDICTS.md.

The primary `LICENSE` in this repo is already genuine MPL-2.0 —
confirmed unchanged. This PR deletes the undocumented root
`license/PMPL-1.0.txt` (full PALIMPSEST-MPL v1.0 body), missed by the
survey classifier's uppercase-only `LICENSE`/`LICENSES` path filter
(lowercase singular `license/` directory).

**Scope**: this is a huge vendored-satellite monorepo. Per the task
brief, this PR touches ONLY the root `license/` directory. It does NOT
touch the ~1,800 further nested per-subproject PMPL `LICENSE` copies
scattered across `satellites/`, `julia-ecosystem/`, and dozens of other
subproject trees (`czech-file-knife/`, `dnfinition/`, `scaffoldia/`,
`techstack-enforcer/`, `well-known-ecosystem/`, etc.) — those are
explicitly out of scope pending a separate owner-routed mass-wave
decision.

No primary LICENSE identity change. No workflow files touched. No
root-level (non-vendored) file references the deleted path by name.
`just must-license-present` and `just trust-license-content` both pass.

**Note for maintainer**: root `README.adoc` line 28 already has an
unrelated dangling reference to `license/MPL-2.0.txt` (a file that has
never existed in this `license/` directory — it held only the
now-deleted `PMPL-1.0.txt`), pre-existing and unrelated to this PR's
deletion; flagging for a separate fix.

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

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: hyperpolymath