fix: resolve open GitHub security findings

Code scanning (js/polynomial-redos, alerts #16 and #17)
-------------------------------------------------------
bowser applies these regexps to attacker-controlled User-Agent strings, and
four of them ran in quadratic time:

  * The "Something else" fallback used /^(.*)\/(.*) / and
    /^(.*)\/(.*)[ \t]\((.*)/. Two unbounded `.*` before a required literal
    make the split ambiguous, so a UA of "/a" repeated backtracks O(n^2).
    Greedy `(.*)` always picks the last `/` that still has the delimiter
    after it, so the second group can never span a `/` -- narrowing it to
    `[^/]*` is exactly equivalent and removes the ambiguity. Verified
    identical on 1,000,000 fuzzed inputs and on the full acceptance corpus.

  * The Linespider and SlackBot version regexps used `(?:-[-\w]+)?` before a
    required `[\s/]`. Since `[-\w]` and `[\s/]` are disjoint the backtracking
    is pure waste, but the engine still walks it once per start position, so
    "linespider-" repeated is quadratic. Bounding the run to `{1,64}` makes
    it linear; no real bot-name suffix approaches 64 characters.

A sweep of all 253 regexp literals in src/ (fuzzed for superlinear scaling,
with the four pre-fix patterns used to confirm the detector works) reports no
remaining superlinear regexps. test/unit/redos.js locks this in.

Actions (actions/missing-workflow-permissions, alerts #5 and #15)
-----------------------------------------------------------------
merge-to-master.yml and draft-or-update-next-release.yml had no `permissions`
block and so inherited the default token. Both now declare least privilege,
matching publish.yml and pull-request.yml.

Dependabot (22 open alerts, all development scope)
--------------------------------------------------
bowser ships no runtime dependencies, so none of these reached consumers, but
they were live in CI. `pnpm audit` goes from 29 advisories to 0:

  * jsdoc 3 -> 4 (with docdash 1 -> 2) drops taffydb, which has no patched
    release, and picks up current markdown-it/linkify-it.
  * coveralls -> coveralls-next 6 drops `request`, which is deprecated with no
    patched release, along with form-data, qs 6.5.x, uuid 3 and tough-cookie 2.
    Same `coveralls` bin and same stdin contract; lcov conversion verified.
  * gh-pages 3 -> 6 clears the critical prototype pollution advisory.
  * pnpm overrides pin the remaining transitive-only advisories to the lowest
    patched release on each existing major.

Verified: pnpm audit clean, lint clean, 346 tests pass (the acceptance corpus
runs against both src/ and the built es5.js), build, package smoke test, and
doc generation.

test/unit/redos.js

@@ -0,0 +1,39 @@
+import test from 'ava';
+import Bowser from '../../src/bowser';
+
+/*
+ * Regression tests for CodeQL js/polynomial-redos. Each input used to drive a
+ * quadratic backtracking path; fixed, they parse in single-digit milliseconds,
+ * so this budget has ~2 orders of magnitude of headroom and is not machine-sensitive.
+ */
+const TIME_BUDGET_MS = 500;
+
+function timeParse(ua) {
+  const startedAt = process.hrtime.bigint();
+  Bowser.parse(ua);
+  return Number(process.hrtime.bigint() - startedAt) / 1e6;
+}
+
+test('parses a Linespider UA made of repeated name tokens in linear time', (t) => {
+  const ua = 'linespider-'.repeat(20000);
+  const elapsed = timeParse(ua);
+  t.true(elapsed < TIME_BUDGET_MS, `took ${elapsed.toFixed(0)}ms, budget ${TIME_BUDGET_MS}ms`);
+});
+
+test('parses a SlackBot UA made of repeated name tokens in linear time', (t) => {
+  const ua = 'slackbot-'.repeat(20000);
+  const elapsed = timeParse(ua);
+  t.true(elapsed < TIME_BUDGET_MS, `took ${elapsed.toFixed(0)}ms, budget ${TIME_BUDGET_MS}ms`);
+});
+
+test('parses an unrecognised slash-heavy UA without a device spec in linear time', (t) => {
+  const ua = `/${'/a'.repeat(60000)}`;
+  const elapsed = timeParse(ua);
+  t.true(elapsed < TIME_BUDGET_MS, `took ${elapsed.toFixed(0)}ms, budget ${TIME_BUDGET_MS}ms`);
+});
+
+test('parses an unrecognised slash-heavy UA with a device spec in linear time', (t) => {
+  const ua = `/${'/a'.repeat(60000)}(`;
+  const elapsed = timeParse(ua);
+  t.true(elapsed < TIME_BUDGET_MS, `took ${elapsed.toFixed(0)}ms, budget ${TIME_BUDGET_MS}ms`);
+});