fix(user.js): resolve DP dormant code, extract shared helpers to a lib

[netravnen]

fix(user.js): resolve DP dormant code, extract shared helpers to a lib

Applies the ratified dp-dormant-clusters triage, reworked per review:
instead of deleting DP's reusable dormant code outright, the pieces
with planned cross-script use move to a new shared fragment,
lib/admincom-shared-helpers.js. For now only the DeskPro script
inlines it, alongside admincom-common.js; whether CP and FP include
it too is deliberately deferred until a concrete caller lands there,
so this commit leaves both untouched. Genuinely superseded or
abandoned code is still deleted (git history preserves it), planned
features are marked with the frozen @StaGeD grammar, and the staged
fetcher's latent bugs are fixed and pinned by a hook-driven test in
the same commit.

The new fragment carries both restored-from-deletion helpers and
live DP internals they depend on: formatSpeedLabel and
getTabSessionStorage (both restored and staged; CP keeps its
identical local getTabSessionStorage twin and is the intended adopter
once the fragment is included beyond DP), the editable-region
predicates (EDITABLE_CONTAINER_SELECTOR, isNodeInsideEditableRegion,
and the restored isAnchorInsideEditableRegion alias), the
IPV4_TEST_REGEX/IPV6_TEST_REGEX pair, getBestApiNetDataItem,
resolveEntityLegalName, and fetchAsnNetworkName -- DP's retired
ASN -> network-name resolver reworked for cross-script use with an
injectable fetchJson transport (the default is same-origin
fetchWithRetry, right for CP/FP if they adopt; cross-origin DeskPro
passes its GM-backed pdbFetch), shared "asn"-type cache persistence,
in-flight dedupe, and a transport-failure-is-not-cached rule. Lib
symbols with no caller yet carry @StaGeD wip markers.

Changes:

• lib/admincom-shared-helpers.js: new shared fragment (see above)
• peeringdb-deskpro-tools.src.js: delete the legacy ASN-name cache
  path (fetchAsnNetworkName's old form, asnNameCache, asnNameInFlight,
  getAsnNameCacheStorageKey, normalizeAsnForCache,
  getCachedAsnNameFromStorage, setCachedAsnNameInStorage) and the
  loose orphans (IX_SHORTCUT_ATTR, ACTION_EMOJI_IX, ensureIxShortcut,
  DUMMY_ORG_ID, attr constants, USER_CACHE_TTL_MS); local copies of
  everything now in the lib removed; the duplicate weaker
  IPV4_TOKEN_REGEX/IPV6_TOKEN_REGEX and the never-consumed
  subjectHinted/RN_SUBJECT_HINT_REGEX stay deleted; stage the
  IP-tooltip cluster, the ASN batch-fetch cluster, and classifyError
  (with the fetchNetixlanByIp bug fixes); add the new lib's @include
  marker and export its helpers via test hooks; bump to 1.7.12
• tests/lib-shared-helpers.test.js: new; covers formatSpeedLabel,
  getTabSessionStorage, the editable-region predicates, and
  fetchAsnNetworkName's cache/dedupe/transport contract through the
  injectable fetchJson transport
• tests/dp-netixlan-ip-cache.test.js: new; pins fetchNetixlanByIp's
  shared cache signatures, null-means-miss, and negative caching
• tests/helpers/browser-shim.js: provide Node.ELEMENT_NODE/TEXT_NODE
  constants (vm contexts have JS intrinsics but no DOM globals, so
  isNodeInsideEditableRegion threw before its logic could run)
• tests/dp-renumber-launcher.test.js: drop subjectHinted assertions
• AGENTS.md: document the new fragment (and its DP-only inclusion)
  plus its test file
• peeringdb-deskpro-tools.user.js regenerated; CP and FP are not
  touched by this commit

Security:

• N/A (no new write paths; staged code remains unreachable in
  production until wired up)

Testing:

• Full suite green from user.js/: 585 pass, 0 fail (1 opt-in live
  skip), including 20 new lib-shared-helpers cases
• Non-vacuity: disabling the resolver's memory-cache read turned the
  two cache-counting cases red; restored, green
• fetchNetixlanByIp non-vacuity as before: the old
  cached !== undefined miss-check turns its cases red
• build --check clean; node --check clean on all three .user.js

Backwards Compatibility:

• getBestApiNetDataItem, resolveEntityLegalName, the TEST regexes and
  the editable-region check keep their exact behavior -- they only
  moved homes; all existing tests pass unmodified
• classifyError keeps every previously-present key/value per branch;
  collectRenumberCandidates' subjectHinted field is removed (its only
  consumer never read it)
• CP and FP ship no change at all in this commit
• No live user-facing behavior changes

Assisted-by: Claude:claude-opus-5
Assisted-by: Claude:claude-fable-5

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