docs: clarify which workspace files are injected into context window (#12937)

* docs: clarify which workspace files are injected into context window (#12909)

The system prompt docs listed bootstrap files but omitted MEMORY.md,
which IS injected when present. This led users to assume memory files
are on-demand only and not consuming context tokens.

Changes:
- Add MEMORY.md to the bootstrap file list
- Note that all listed files consume tokens on every turn
- Clarify that memory/*.md daily files are NOT injected (on-demand only)
- Document sub-agent bootstrap filtering (AGENTS.md + TOOLS.md only)

Closes #12909

* docs: mention memory.md alternate filename in bootstrap list

Address review feedback: the runtime also injects lowercase memory.md
(DEFAULT_MEMORY_ALT_FILENAME) when present.

* docs: align memory bootstrap docs (#12937) (thanks @omair445)

---------

Co-authored-by: Luna AI <luna@coredirection.ai>
Co-authored-by: Sebastian <19554889+sebslight@users.noreply.github.com>

docs/reference/token-use.md

@@ -18,7 +18,7 @@ OpenClaw assembles its own system prompt on every run. It includes:
 - Tool list + short descriptions
 - Skills list (only metadata; instructions are loaded on demand with `read`)
 - Self-update instructions
-- Workspace + bootstrap files (`AGENTS.md`, `SOUL.md`, `TOOLS.md`, `IDENTITY.md`, `USER.md`, `HEARTBEAT.md`, `BOOTSTRAP.md` when new). Large files are truncated by `agents.defaults.bootstrapMaxChars` (default: 20000).
+- Workspace + bootstrap files (`AGENTS.md`, `SOUL.md`, `TOOLS.md`, `IDENTITY.md`, `USER.md`, `HEARTBEAT.md`, `BOOTSTRAP.md` when new, plus `MEMORY.md` and/or `memory.md` when present). Large files are truncated by `agents.defaults.bootstrapMaxChars` (default: 20000). `memory/*.md` files are on-demand via memory tools and are not auto-injected.
 - Time (UTC + user timezone)
 - Reply tags + heartbeat behavior
 - Runtime metadata (host/OS/model/thinking)