ui(memory): capitalize --table headers and shorten UUID column

[codeaholicguy]

Current output

⚠ No memory items found matching "capacity"

With results (--table):

  id                                   title                    scope
  ────────────────────────────────────────────────────────────────
  b47ce05b-89d7-4895-a85a-61225ecfaa44 Implemented memory search… project:ai-devkit

Problems

1. Lowercase headers ["id", "title", "scope"] — every other table in the CLI capitalizes headers (Quota, Agent, Name, Check).
2. Untruncated UUID dominates column width: the id column prints the full 36-char UUID, forcing title to truncate; the short form used nowhere else. For a human-facing table the first 8 chars (or a --full-ids flag) would be enough — the full ID is already available in the default JSON output for copy/paste.
3. Empty-state is good (⚠ line with the query echoed) but gives no next step, unlike skill list which prints an ℹ tip line — the two empty-states follow different patterns.
4. Minor: table flag is opt-in (--table) while JSON is default — fine, but the flag's help text says "with id, title, and scope" which leaks the lowercase header choice as a contract.

Expectation

  ID          Title                      Scope
  ────────────────────────────────────────────────
  b47ce05b    Implemented memory search  project:ai-devkit

• Capitalized headers: ID, Title, Scope.
• Short ID in the table (first segment of the UUID); full ID stays in --json (and memory update <id> should keep accepting it, or document short-ID acceptance).
• Empty state adds a dim tip line, e.g. Tip: store knowledge with "ai-devkit memory store".

Files: packages/cli/src/commands/memory.ts (search --table render ~L107–120)