feat(control-plane): show the coding agent's logo on documents and memories

[nicoloboschi]

What

Documents retained by hindsight-coding-agents say which coding agent wrote them —
metadata.harness = "claude-code" plus a harness:<id> tag — but the control plane
rendered that as just another key=value chip, indistinguishable from session_id
while scanning a column of near-identical conversation:<uuid> IDs.

This resolves the value to the agent's logo, as a convention rather than a one-off:

• Documents table — the mark trails the "Updated …" line. It deliberately does not
  lead the ID: as a leading mark it only exists on some rows, so every ID shifted
  horizontally depending on whether its document had one. The now-redundant harness=
  metadata chip is dropped from the row (chip slots there are scarce); the
  harness:<id> tag stays, because clicking it filters the list.
• Document dialog — logo beside the title, plus a Harness row.
• Memory dialog — a Harness card in the Document tab, next to the document's tags.
  Memory units inherit the document's metadata at retain time, so the value is read off
  the memory itself and needs no second lookup. That tab also gained the document's
  metadata, rendered with the shared MetadataChip instead of a new treatment.

The convention

src/lib/harness-logo.ts is the one place the mapping lives, and it holds exactly the
ids that integration emits — claude-code, codex, cursor-cli, gemini, opencode
(see its src/harness/hook-lifecycle.ts and src/harness/registry.ts, added in #2522).
A test asserts the registry stays in step with that set: an id nothing writes is a logo
nothing renders. Adding an agent there means adding it here in the same change — copy its
icon from hindsight-docs/static/img/icons/ into public/img/harness/, add one entry.

An unregistered harness is not an error: no logo, and the value still shows as ordinary
metadata. Written up in CLAUDE.md.

Monochrome marks (Codex, Cursor CLI) are flagged so only they get dark:invert —
inverting a multi-colour mark like Gemini would misrepresent the brand.

Notes

• The Harness label moved to the shared common namespace now that two views use it;
  memoryDetailModal.sectionMetadata reuses each locale's existing translation of
  "Metadata" rather than inventing a second wording. All 10 locales updated.
• getMemory's client type gained the metadata field the endpoint already returned.
• Observations have no Document tab, so they show no harness — out of scope here.
• Expect a textual conflict with hindsight-coding-agents: harness-pluggable long-term memory for coding agents #2522, which also touches documents-view.tsx.

Testing

• tests/lib/harness-logo.test.ts — resolution, harness:<id> tag fallback, metadata
  precedence, normalisation, registry-matches-emitted-set, and a guard that every entry's
  asset actually ships in public/.
• Verified in the running control plane against a real bank: logos in the table, both
  dialogs, and the Codex mark still legible in dark mode.