feat(sources v1): the agent locates files itself — ls/find/grep + tool-call cards

User pivot (2026-09-19): no attachments UI at all. Pasting paths is native
for technical users and alien for everyone else - so the agent gets the
tools to find what the learner merely NAMES. The learner communicates in
messages; the agent locates and reads. Zero cross-stream seams: paths
already live in tool parts, so the sources "list" is the transcript.

- ls/find/grep: pi-verbatim schemas, descriptions, and output formats
  (fd's glob semantics, rg's path:line: match format, pi's truncation
  notices), ported to pure Node - no binaries, no shell-out, read-only by
  construction. Deltas from pi: home-anchored resolution (the harness has
  no cwd), .gitignore replaced by hard noise exclusions
  (node_modules/.git/Library/.Trash), 10s walk timeout with partial results.
- read: description swapped to pi-verbatim (doctrine moved to the prompt);
  relative paths now resolve against the learner's home like the rest.
- prompts/shared/05-learner-files.md: one minimal doctrine fragment
  composed into BOTH agents (composeInstructions grew a shared/ dir,
  before the agent's own fragments). teacher/30-jobs.md keeps only the
  pdf-dispatch addendum.
- ToolCallCard: the generic quiet tool-call card the user specced -
  collapsed one-liner (tool name + headline argument), expandable to full
  input/output, errors red, image payloads never render. Registered for
  read/ls/find/grep.
- ui-message.ts: TeacherUITools entries for the four tools (mechanical).
- tests: fs-tools suite (glob semantics, pi formats, exclusions, limits),
  registry/card renders, shared-fragment composition pins, tool-registry
  key updates, read re-anchor.

src/core/ui-message.ts

@@ -38,6 +38,23 @@ export type TeacherUITools = {
 	/** The pdf dispatch tool (sources v0): fire-and-forget ack output like
 	 *  research — the brief arrives later as a steer message. */
 	pdf: { input: PdfToolInput; output: string };
+	/** The learner-filesystem tools (sources v1, both agents, always-on):
+	 *  read may return an image-bearing result; the rest are plain text. */
+	read: { input: { path: string; offset?: number; limit?: number }; output: unknown };
+	ls: { input: { path?: string; limit?: number }; output: unknown };
+	find: { input: { pattern: string; path?: string; limit?: number }; output: unknown };
+	grep: {
+		input: {
+			pattern: string;
+			path?: string;
+			glob?: string;
+			ignoreCase?: boolean;
+			literal?: boolean;
+			context?: number;
+			limit?: number;
+		};
+		output: unknown;
+	};
 };
 
 export type TeacherUIDataParts = {