fix(web): usable past-conversation list, and search that finds past sessions

Two home-screen reports from @jordan8037310, both about history that is
present but unreachable.

#260 — "Resume Conversation" rendered 4 rows, then a button that appended
every remaining row into a `max-height: 240px` box, so 35 conversations
landed in a four-row scroll well with no ordering or filtering. Rendering
now goes through `_renderHistoryList()` over a cached corpus: 10 rows to
start, Show more/Show less that grows and shrinks the box (the height cap
is class-driven, `.history-list.expanded`), plus a filter box (name,
folder, #case label, prompts), a sort control (recent / name / folder,
pinned rows still first) and a shown-of-total count. A filter implies
expansion, so every match is visible, and the whole header hides as one
unit while a federated search is active. The A-Z sort keys off the same
string the row renders, since most rows are transcript-backed and carry
no session name at all.

#261 — the search box could not match a past project by folder name:
`harvestSources()` built its session corpus from the live in-memory map,
while past sessions come from `/api/sessions/unified` (lifecycle log +
transcript scan). Folding that scan into the request path would have cost
the search its no-filesystem-reads property, so the corpus arrives via a
bounded snapshot instead: `session-history-index.ts` is published as a
side effect of `/api/sessions/unified` (the home screen fetches it on
open, which is the same screen the search box lives on) and rebuilt
fire-and-forget, single-flight and TTL-guarded when a search finds it
stale. A result for a closed session now resumes the conversation rather
than selecting a tab that no longer exists, and is badged RESUME.

The snapshot is stored unscoped with a per-row owner and re-filtered
through canAccessOwned() on read, so multi-user sees exactly what
/api/sessions/unified exposes: own sessions only, host-wide transcript
history admin-only. Live rows are harvested first and win the dedupe.

Verified end-to-end against a real instance with 60 past sessions: cold
process answers its first search without history and its second with it;
folder-name queries return resume targets; clicking one posts the right
resumeSessionId + workingDir.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/types/search.ts

@@ -22,15 +22,19 @@ export type SearchSourceType = 'session' | 'event' | 'file';
 
 /** Where the frontend should jump when a result card is activated. */
 export interface SearchJumpTarget {
-  /** Kind of navigation target. */
-  kind: 'session' | 'run-summary' | 'file-preview';
+  /**
+   * Kind of navigation target. `resume-session` marks a session that is no longer
+   * running: selecting it has to REPLAY the conversation rather than switch to a
+   * tab that does not exist.
+   */
+  kind: 'session' | 'run-summary' | 'file-preview' | 'resume-session';
   /** Owning Codeman session id (always present — every result is session-scoped). */
   sessionId: string;
   /**
    * Secondary identifier for the target:
    * - kind 'run-summary': the run-summary event id
    * - kind 'file-preview': the attachment history item id
-   * - kind 'session': undefined (the sessionId is sufficient)
+   * - kind 'session' / 'resume-session': undefined (the sessionId is sufficient)
    */
   targetId?: string;
   /**
@@ -38,6 +42,16 @@ export interface SearchJumpTarget {
    * server-private external paths are intentionally omitted to avoid leakage.
    */
   relativePath?: string;
+  /**
+   * `resume-session` only: the Claude conversation UUID to resume, when it differs
+   * from the Codeman session id (resumed and `/clear`-respawned sessions).
+   */
+  claudeSessionId?: string;
+  /**
+   * `resume-session` only: the directory to resume in. Already visible in the
+   * result snippet for session rows, so this exposes nothing new.
+   */
+  workingDir?: string;
 }
 
 /** A single typed search result card. */