feat(agent): interactive TUI launcher + identity + TOOLS.md (#35)

- scripts/agent.sh <name>: launches interactive pi TUI in the container
  with contracts + optional mission + agent identity + named session +
  optional workspace/tools; the Mosaic alternative to vanilla pi
- pi adapter: MOSAIC_INTERACTIVE branch (clean TUI, no -p, no initial
  prompt); headless exec rebuilt via positional args (no word-splitting
  on the request); MOSAIC_AGENT_NAME optional in headless
- loader: AGENT IDENTITY section when the launcher names the agent
- compose: fixed command removed (request defaults live in run-agent.sh);
  MOSAIC_INTERACTIVE/MOSAIC_AGENT_NAME passthrough
- docs/TOOLS.md: full on-demand tool reference; AGENTS.md routes to it
- RELEASE -> 0.0.8 (container change); build verified

Closes #35

src/run-agent.sh

@@ -1,13 +1,22 @@
 #!/bin/sh
-# One-shot agent dispatcher inside the container.
+# Agent dispatcher inside the container.
 #
-# 1. Loads the contract-generated system prompt (contracts + optional
-#    mission section from MOSAIC_MISSION_FILE).
-# 2. Dispatches to /opt/mosaic/adapters/<MOSAIC_ADAPTER>/adapter.sh per
-#    the contract in /opt/mosaic/adapters/README.md.
+# Headless (default): loads the contract-generated system prompt, then
+# dispatches one request to /opt/mosaic/adapters/<MOSAIC_ADAPTER>/adapter.sh
+# (contract: /opt/mosaic/adapters/README.md).
+#
+# Interactive (MOSAIC_INTERACTIVE=1, from scripts/agent.sh): same prompt,
+# but the adapter opens the full pi TUI with no initial prompt - the human
+# drives from there.
 set -eu
 
-REQUEST="${*:-Return your startup marker and nothing else.}"
+REQUEST=""
+if [ "${MOSAIC_INTERACTIVE:-}" != "1" ]; then
+    # Headless: args are the request; default is the startup verification
+    # request used by hello/verify.
+    REQUEST="${*:-Return your startup marker and nothing else.}"
+    export MOSAIC_REQUEST="$REQUEST"
+fi
 
 ADAPTER="${MOSAIC_ADAPTER:-pi}"
 case "$ADAPTER" in
@@ -28,6 +37,5 @@ fi
 /opt/mosaic/src/load-contracts.sh /opt/mosaic/contracts /var/lib/mosaic/system-prompt.md
 
 export MOSAIC_SYSTEM_PROMPT_FILE="/var/lib/mosaic/system-prompt.md"
-export MOSAIC_REQUEST="$REQUEST"
 
 exec "$ADAPTER_SCRIPT"