feat(browser): deterministic private_browser lifecycle (Wave 5A)

Own each agent-browser session as a browser tree: the daemon's POSIX
session, its runtime files and its Chrome profile. Timeouts, launch
failures, bootstrap recovery, cancellation and shutdown clean that tree
and verify nothing survives, instead of killing only the daemon and
orphaning Chrome. Per-call cleanup no longer sweeps every Chrome under
the runtime TMPDIR.

Sessionless calls get an ephemeral browser closed before returning.
Actions on one session are serialized. Recovery is bounded by one
deadline with at most one retry for local HTML open, and the retry flag
is no longer model-visible. Observations after a failed navigation are
marked stale. read URL navigates and extracts in one batch because
agent-browser has no read command. Results carry a browser_lifecycle
receipt with stages, timings, ownership and cleanup evidence.

Playwright MCP tool calls are bounded by
ODYSSEUS_BROWSER_MCP_CALL_TIMEOUT_S and are not retried. research_navigator
now passes timeout_ms.

website/configuration-reference.md

@@ -21,7 +21,7 @@ described as a switch that turns something off, the read rejects `0`, `false`,
 `no` and `off` and treats everything else as on. The `Default` column is the
 value the code falls back to when the variable is unset, quoted from the source.
 
-The source tree reads **108** `ODYSSEUS_*` variables: 78 an operator may want to set, and 30 that are internal - sentinels, fixture switches, capture hooks and development tooling. The internal ones are listed too, in their own section, so this page can be checked against the source mechanically.
+The source tree reads **109** `ODYSSEUS_*` variables: 79 an operator may want to set, and 30 that are internal - sentinels, fixture switches, capture hooks and development tooling. The internal ones are listed too, in their own section, so this page can be checked against the source mechanically.
 
 > This page is generated. Edit `scripts/generate_env_reference.py` and
 > re-run it; `tests/test_env_reference.py` enforces that the committed page
@@ -86,10 +86,11 @@ The source tree reads **108** `ODYSSEUS_*` variables: 78 an operator may want to
 | `ODYSSEUS_BROWSER_EXECUTABLE` | `''` | `src/builtin_mcp.py:114` | Absolute path to the Chrome or Chromium binary. Empty searches the usual names, then lets Playwright MCP pick its own browser. |
 | `ODYSSEUS_BROWSER_ISOLATED` | `'1'` | `src/builtin_mcp.py:139` | Security-relevant. On by default, adding `--isolated` so each browser session starts clean. Set 0, false or no to keep a persistent profile. |
 | `ODYSSEUS_BROWSER_MCP_CACHE` | `os.path.join(base_dir, 'data', 'local', 'playwright-mcp-cache')` | `src/builtin_mcp.py:229` | Cache directory handed to the browser MCP server, so its npm download survives a container rebuild. |
+| `ODYSSEUS_BROWSER_MCP_CALL_TIMEOUT_S` | `'90'` | `src/mcp_manager.py:27` | Upper bound in seconds for one browser MCP tool call. A call that exceeds it fails without being retried. |
 | `ODYSSEUS_BROWSER_MCP_REQUIRE_CACHE` | `''` | `src/builtin_mcp.py:90` | Truthy refuses to start the browser MCP server unless its npm package is already in the npx cache, instead of installing it at startup. |
-| `ODYSSEUS_BROWSER_NAMESPACE` | `'odysseus-ui'` | `src/agent_tools/web_tools.py:2441` (+5 more) | Namespace for the detached agent-browser daemon's pid files, so two runtimes on one machine do not terminate each other's browsers. |
+| `ODYSSEUS_BROWSER_NAMESPACE` | `'odysseus-ui'` | `src/agent_tools/web_tools.py:100` (+3 more) | Namespace for the detached agent-browser daemon's pid files, so two runtimes on one machine do not terminate each other's browsers. |
 | `ODYSSEUS_BROWSER_NO_SANDBOX` | `'1'` | `src/builtin_mcp.py:142` | Security-relevant. On by default, adding `--no-sandbox` because the Docker image cannot use the Chromium sandbox. Set 0, false or no to keep it. |
-| `ODYSSEUS_BROWSER_SCREENSHOT_DIR` | *unset* | `src/agent_tools/web_tools.py:3135` | Where private-browser screenshots are written. Falls back to the container path, then the system temp directory. |
+| `ODYSSEUS_BROWSER_SCREENSHOT_DIR` | *unset* | `src/agent_tools/web_tools.py:3423` | Where private-browser screenshots are written. Falls back to the container path, then the system temp directory. |
 
 ### Container and workspace mounts
 
@@ -256,7 +257,7 @@ reads three ways, because no single pattern covers the codebase:
   lines, so one read lives inside a string literal.
 
 The three passes are not redundancy. A line-based grep for a direct
-`os.environ.get("ODYSSEUS_...` call finds 80 of the 108 variables on this
+`os.environ.get("ODYSSEUS_...` call finds 81 of the 109 variables on this
 page. What it misses is reads through an env-reader helper, reads whose call
 spans more than one line, reads whose variable name is held in a module
 constant, and reads through a mapping passed in as an argument - which is the